The world's top museum curators urged U.S. authorities to seal Iraq's borders to stop the flow of looted antiquities, a loss that one said was the worst calamity for a national art collection since World War II.

Delegates to Tuesday's meeting at the British Museum also urged the U.N. Security Council to ban trade in Iraqi artifacts.

"American control at the border is almost zero," said Donny George, research director of Iraq's National Museum in Baghdad. "Anyone can take anything and go out. .... the bleeding of antiquities is still going on."

The British Museum and UNESCO brought experts from the Louvre in Paris, New York's Metropolitan Museum of Art, Russia's Hermitage and the Berlin Museums to hear a report from George and British Museum Near East curator John Curtis, who returned Monday after a week in Iraq.

"This is without question the greatest disaster to a national collection since the Second World War," British Museum director Neil MacGregor told BBC radio earlier.

After Saddam Hussein's government fell to a U.S.-led coalition this month, looters stole and smashed priceless archaeological treasures from the Baghdad museum. The museum in the northern city of Mosul also was pillaged, and Baghdad's Islamic Library was set afire.

With funding offered from individuals and governments, the British Museum will oversee the training of experts who will go to Iraq and help piece the country's archaeological heritage back together, MacGregor said after the meeting.

UNESCO said it would soon send a panel of experts to Iraq to begin compiling a database of the country's missing artifacts, that would be shared with police around the world, said assistant director-general Mounir Bouchenaki.

Many Iraqis criticized U.S. troops for doing little to stop the theft, and museum experts echoed that view. The United States has said it was surprised by the rampage and said American troops were too occupied by combat to intervene when they reached Baghdad.

George said museum staff members begged U.S. troops to park their tanks nearby to discourage looting.

"They told him they did not have orders for that. Was it done intentionally? I don't know," he said. "You should ask them why they did not protect a place they knew contained the heritage of mankind."

George said he saw no U.S. presence when he recently crossed the Iraqi-Jordanian border, but that Jordanian border officials said they had confiscated 12 boxes of objects and documents.

"It's very extraordinary ... that with American troops in Baghdad, American troops almost at the gates of the museum, this was allowed to happen," MacGregor said.

He said it was unclear whether the looting had been carried out to order by thieves acting for private art collectors.

"It's clear that there is a flourishing trade in illicit Mesopotamian antiquities, so I think a lot of it would have been stolen for the trade," he told the BBC. "That's not the same as for a specific collector."

Ancient Mesopotamia — modern-day Iraq — was the cradle of civilization, and Iraq's museums held priceless, millennia-old collections of Babylonian, Sumerian and Assyrian artifacts.

Gen. Tommy Franks, commander of coalition forces in Iraq, said Monday that Iraqis had begun to respond to American appeals to return looted goods. Over the weekend, U.S. forces had began broadcasting radio messages offering rewards for the antiquities' return.

The U.S. Central Command said more than 100 items had been handed in, including priceless manuscripts, a 7,000-year-old vase and one of the oldest recorded bronze bas relief bulls.

In an interview with The Associated Press, Franks said it did not appear that the looting had been carried out by an organized network of thieves.

"We're apt to find where an individual person decided he or she could take some of the antiquities and save them for a rainy day," he said from coalition headquarters in Doha, Qatar.

But Professor Peter Stone, who advised the British military on Iraq's historic sites, disagreed, saying some of the items were probably stolen for specific clients.

"I would be very surprised if it were not the case that some of it had been stolen to order — although I have no cast-iron evidence of that," said Stone, an archaeology expert at Newcastle University.

Among the items believed lost from the Baghdad museum are an alabaster vase from 3200 B.C. and bronze reliefs from 3500 B.C.