In the months leading up to the war in Iraq, US scholars repeatedly urged the Defence Department to protect Iraq's priceless archaeological heritage from looters, and warned specifically that the National Museum of Antiquities was the single most important site in the country.

Late in January, a mix of scholars, museum directors, art collectors and antiquities dealers asked for and were granted a meeting at the Pentagon to discuss their misgivings.

McGuire Gibson, an Iraq specialist at the University of Chicago's Oriental Institute, said on Sunday that he went back twice more, and he and colleagues peppered Defence Department officials with email reminders in the weeks before the war began.

"I thought I was given assurances that sites and museums would be protected," Dr Gibson said. Instead, even with US forces firmly in control of Baghdad last week, looters breached the museum, trashed its galleries, burnt its records, invaded its vaults and smashed or carried off thousands of artefacts dating from the founding of ancient Sumer around 3500 BC to the end of Islam's Abbasid Caliphate in 1258AD.

Asked on Sunday about the looting of the museum, US Defence Secretary Donald Rumsfeld blamed the chaos that ensues "when you go from a dictatorship" to a new order.

Iraq also has 13 regional museums at risk, including another world-renowned facility in the northern city of Mosul, as well as thousands of archaeological sites, ranging from the fabled ancient cities of Ur, Nineveh, Nimrud and Babylon to medieval Muslim villages abandoned in the country's vast western reaches.

"To the extent possible, and as soon as though it were yesterday, someone needs to post border guards to intercept antiquities as they try to leave the country," said archaeologist and art historian John Russell, of the Massachusetts College of Art.

In January, a statement from the Archaeological Institute of America called on "all governments" to protect cultural sites during an expected conflict and in its aftermath. Dr Gibson and others said they were especially concerned because of the example of the 1991 Gulf War.

Allied forces scrupulously avoided targeting Iraqi cultural sites during the bombing of Baghdad 12 years ago.

But the end of that war kicked off a looting rampage, and eventually allowed systematic smuggling to develop. Artefacts from inadequately guarded sites were dug up and hauled away during the 12 years between the wars. "We wanted to make sure this didn't happen again," Dr Gibson said.

"They said they would be very aware and would try to protect the artefacts," Dr Gibson said, recalling January meetings with Pentagon officials charged with target selection and the protection of cultural sites.

Pentagon officials knowledgeable about those meetings referred questions to the public affairs office, which said the military had tried to protect the sites.

Since the 1920s, Iraq has required that anyone digging within its borders file a report with the museum. More recently, expeditions had to submit excavated material to the museum for cataloguing after each year's digging season.

Looters apparently burnt or otherwise destroyed most of those records last week, but Dr Gibson suggested scholars worldwide could duplicate the archive by copying their files and reports and resubmitting them to Iraqi authorities.

The museum's artefacts are another matter. Although the damage done is almost certainly catastrophic, Dr Russell said: "It's going to be a matter of weeks or months before we're going to be able to identify any particular thing". The cultural heritage of Iraq, the home of ancient Mesopotamia, encompasses the Sumerians, Akkadians, Babylonians, Assyrians, Chaldeans, Persians, Greeks, Romans, Parthians, Sassanids and Muslims, to name only the best-known civilisations.