No one in Baghdad knew who he was or the risks he was taking. Apart from a select group of trusted friends, they still don't. The telephones and the internet haven't worked here since the collapse of the regime, so the Iraqis never had a chance to read the diaries of the Baghdad Blogger.

Outside the country, many didn't even believe that the man who wrote only under the sobriquet Salam Pax truly existed. It was the great irony of the war. While the world's leading newspapers and television networks poured millions of pounds into their coverage of the war in Iraq, it was the internet musings of a witty young Iraqi living in a two-storey house in a Baghdad suburb that scooped them all to deliver the most compelling description of life during the war.

As with so much in Iraq, it was never meant to be like this. In June last year, Salam (this much of his name, at least, is real) was a recently graduated architect, aged 29, living at home with his parents and brother in Baghdad. His best friend was Raed, 25, a Palestinian-Jordanian he had met while studying architecture, who was taking a masters degree in Jordan. Raed was at best an infrequent email correspondent and so Salam started writing up his news from home on a weblog, a site on the internet where he could post his scribblings as often as he liked for his friend to read. He called it: Where is Raed?

No one else bothered to look at it. "The first two months were just: that girl got married, I had the flu, he had I don't know what. Stupid stuff," says Salam. "I never thought there would be this much of a fuss about the whole thing."

Soon, however, he began to search out other "bloggers" posting on the internet. Few were writing in English from the Arab world, and those that did wrote in heavily religious overtones. That was enough to encourage Salam to put his head above the parapet and one day he identified himself on a bloggers' website as an Iraqi. "I was saying, 'Come on, look, the Arabs here: sex, alcohol, belly dancers, TV shows, where are they?' All you saw was people talking about God and Allah. There was nothing about what was happening here."

As he wrote in more detail, he began to touch more often on the unspoken hardships of life in Iraq under the paranoid regime of Saddam Hussein. He could hardly have taken a greater risk if he had tried. More than 200,000 people went missing under Saddam, many for far lesser crimes than the open criticism of the regime that Salam voiced in his writings. Now that the regime has fallen, human rights workers are tripping over mass graves in Iraq every few days as they trawl through the legacy of 23 years of unimaginable brutality and persecution.

Like all Iraqis, Salam was familiar with the dangers. At least four of his relatives had gone missing. In the past year, for no apparent reason, one of his friends was summarily executed, shot in the head as he sat in his car, and two others were arrested; one was later freed and another, a close friend, has never returned.

Not only had Salam criticised the regime, he had written openly about the fact that he is gay. It was a frank admission in a repressive dictatorship and one that, even in the new, postwar Iraq, which at heart is still a conservative, Islamic society, represents a significant risk. And so he continues to guard his identity. "I am not going to be the first one to carry the flag. I hide behind computer screens," he says.

Despite the risks, Salam soon became hooked on his daily diary. He gave simple but honest descriptions of life at Hotel Pax, as he called his family home, which was fast filling up with anxious relatives. He talked equally freely about the soaring price of tomatoes and the sudden arrival of the feared Ba'ath party militia, who, to the neighbours' horror, set up a gun position in an empty house on his street. He wrote either in the office of the architectural firm he was representing in Baghdad, or at home, in his chaotically untidy bedroom.

Screens cover the windows to keep the midday sun away from his three computers, each of which has been opened up into a sprawling tangle of wires and circuit boards. A poster from the film The Matrix hangs on the wall, looking down on a jumble of computer books and CDs strewn over the floor. Pages of website addresses and computer commands are tacked to the wall above his screen. It was here that Salam would sit and talk endlessly about the impending war with Raed, who returned to Baghdad before the war, and the friend he describes only as G - Ghaith, another young, intelligent, eloquent architectural graduate who spent much of his adult life dodging military service. They talked eagerly about the demise of Saddam, but they were scared too. Scared of being called up for military service because all young men were reservists, and scared of being obliterated by an American bomb.

But Salam's writing is remarkably free of sentimentality even as the approaching war becomes inevitable. "I helped my mother pack things today," he wrote in a posting on February 16, a month before the invasion. "We have not decided to leave Baghdad if 'it' happens, but just in case we absolutely have to. We are very efficient packers, me and my mom. The worst packers are the emotional ones. The 'Oh-let's-remember-when-I-bought-this-thing' packers, we just do it in cold blood. We have done this quite often; we are serial packers."

Salam is shy, but he has a quick and sometimes cynical humour that flows easily through his writing. Yet occasionally his wit choked on the images of death and war that appeared on the family television screen, beamed into the Hotel Pax from an illegal satellite dish on the roof. "On BBC we are watching scenes of Iraqis surrendering," he wrote on March 21, in the first week of combat. "My youngest cousin was muttering, 'What shame' to himself. Yes, it is better for them to do that, but still, seeing them carrying that white flag makes something deep inside you cringe."

By now his weblog had blossomed in confidence from idle chat to startling reportage that seems to have been driven by an underlying urge to resist the regime and to document its fall. He is almost offended when I ask later why he risked staying in Baghdad during the war, rather than escaping abroad which, as a well-off, educated Iraqi, would not have been hard. "I absolutely had to stay. This is your country, this is your place. I had to see what was going to happen."

Yet in the final weeks before the impending conflict, he became increasingly anxious that the men of the Mukhabarat, the feared Iraqi intelligence agency, were on to him. "They were not only paranoid, they were going crazy," he says. At one point the regime blocked access to the website on which he was posting his writing, blogspot.com. "There was the possibility that they knew. I spent a couple of days thinking this is the end. And then you wait for a couple of days and nothing happens and you say, 'OK, let's do it again.' Stupid risks, one after another."

Reports of his writing began to filter into the newspapers in Britain and the US. At one point during the war, while he was still able to access the internet and send his writing, the Arabic radio services of the BBC and the Voice of America ran stories on him. His father heard the reports and for the first time guessed that that it was his son they were referring to. "When he heard this, he was sure that something bad would happen." By now 20,000 people were regularly reading Salam's words and his writing became the most linked-to diary on the internet.

Then suddenly, around ten days into the war, the ever paranoid Iraqis closed down all internet access. Unable to post his diaries, Salam continued to write: "After eight months, it became a habit." Sometimes, when the generator was running, he used his computer. Mostly he wrote in a notebook, describing the bombings across Baghdad and the increasingly frenetic Iraqi army and fedayeen.

"There will be excellent, amazing, very important stories to be told by lots of people. We, sitting in Baghdad in our protected four walls, were never going to be these stories. There are people who went through much more," he says.

Two weeks ago he collected his writings together and sent them by email to Diana Moon, a trusted fellow blogger from New York, who posted them on the site. Salam is modest about what he has written, but furious, too, with those who doubted his authenticity. At one point he changed the name of the weblog to simply Dear Raed. Many thought the palindrome hinted that Salam Pax didn't exist, but was an agent of Iraqi or US intelligence. His allusions to David Bowie and Hollywood movies seemed unusually familiar and so his identity was questioned.

In fact, his experience of the west dates back to two long periods of his childhood spent living in Vienna, where his father worked as a businessman. He lived there alone for eight years as a student, returning reluctantly to Baghdad in 1996 because his parents called him back. He regarded the doubters as culturally arrogant, unable to accept that an Iraqi in Baghdad could share their interests and write on them eloquently and with humour. "I am this little no one who actually is a kind of a foreigner in his own culture. I don't listen to Arabic music a lot, I don't read that much, I think every single Arabic newspaper is a tool to whatever government. It was making me angry, it was annoying me, I didn't see why I had to take all this shit."

Much of the criticism came from Americans who favoured the war and were riled by Salam's dismissive criticism of US ambitions in Iraq. He argued endlessly with Raed and Ghaith about whether the war was justified. He was reluctant to cheer the US invasion in his writings but, like most Iraqis, says only a foreign invasion could have overthrown Saddam and so accomplished what most of the population longed for.

But, again like most, he is bitter about the looting and lawlessness which for the past six weeks have gripped Baghdad. "The Americans are not taking control of the situation and stopping it. There is no way they could wash their hands clean of it," he says. "Two months like this is too much, three months is a disaster."

Electricity is still intermittent at best, government is a long way from restored. Most ministries are gutted, some of them are still smoking. What message does it send to frustrated Iraqis that only the oil ministry has been protected by US troops? Already some are talking of Saddam's era as the good days, Salam says.

The former dictator and his two loathed sons are still on the run. The weapons of mass destruction, the fragile premise on which the war was based, have been not been found. Now some hardline Shia clerics are becoming increasingly fractious, taking advantage of the power vacuum and threatening to ban alcohol, cinema and prostitution on pain of execution. The Baghdad blogger may still have the most important chapters of his diary left to write