At least one in ten of the objects in Iraq's national museum are missing, its director has said.
Muayyad Damerji, with an example of a missing object
Dr Nawalaal Mutawalli told a press conference at the British Museum in London that some 13,000 objects had gone missing from the Baghdad institution's storage room in the days following the fall of Saddam Hussein.
Mobs of looters attacked the building, leaving a trail of devastation after US-led forces seized the Iraqi capital in April.
Dr Mutawalli said museum staff had only searched through part of the storage room, so the picture could still be much worse.
In addition, 47 pieces had been taken from its exhibition room - with seven described as "very important masterpieces".
The missing treasures include brick bearing inscriptions of kings, pottery from different periods, figurines and terracottas.
Staff have only recently been able to start a thorough search of the museum because they had no electricity until they obtained a generator.
Its director of research, Donny George, said some 1,500 missing treasures had been returned, many by locals who said they were protecting them until the museum was properly secured by troops.
Italian forces guarding the Baghdad museum
Archaeology professor Elizabeth Stone, from Stony Brook University in New York, added that most of the 10,000 historic sites across Iraq had been looted in one way or another, although Babylon and Ur had remained untouched.
"Looting of archaeological sites was very rare before the first Gulf War but it has escalated extraordinarily since the last war and there is not a lot of structure to protect them," she said.
"Some of these sites are almost completely gone. The impact in terms of archaeology is enormous."
She said antiquities were being traded in markets - souks - but the US military were "too scared to go in there because people were going to get killed".
"It's not an easy thing to do to shut these down," she said.
An international conservation team will begin work trying to restore broken objects at the Baghdad museum in the autumn.
But John Curtis, of the British Museum's ancient near east department, said it was doubtful that all the pieces could be restored.