Iraqi museums were pillaged of treasures dating back 5,000 years during looting that occurred amid the chaos of the 2003 U.S.-led invasion that toppled Saddam Hussein.
"Rich people are buying stolen material," museum director Donny George told reporters. "Money is going to Iraq and they (terror groups) are buying weapons and ammunition to use against Iraqi police and American forces," he said.
Police in the United States are doing an "excellent" job of curbing the flow of stolen artifacts there, but "a lot of material is just penetrating the country," George said. "A lot of these objects are actually going to the United States."
"People in the international community must stop buying these things ... This money is going to the terrorists," he said at a UNESCO conference on Iraq's cultural heritage.
Iraqi Culture Minister Nouri Farhan al-Rawi, also speaking at the news conference, noted: "There was a great deal of looting when coalition forces arrived. Today, coalition forces are helping us a lot, and there are no more cases of looting or theft."
Of the 15,000 objects stolen from the national museum, almost 4,000 have been returned to the country and more than 4,000 others are in neighboring countries for safekeeping, George said.
It is impossible to assess the scale of theft or damage at archaeological sites outside Baghdad, said a committee of experts gathered at UNESCO, the Paris-based U.N. cultural agency.
Farhan al-Rawi urged UNESCO to help the Iraqi government transform 170 buildings - including Saddam's former palaces and other government buildings - into cultural centers, public libraries and tourist centers. Some are located in Baghdad's heavily fortified Green Zone, which houses the Iraqi government and U.S. Embassy.
"Today, the Ministry of Culture is not in a position to recuperate and run the palaces," said Farhan al-Rawi, noting that guards outside the national museum were sometimes shot at.
The committee praised efforts by several countries holding Iraqi treasures for safekeeping, including Jordan, Kuwait, Syria, Italy, Saudi Arabia and the United States. But it said more cooperation was needed from Turkey and Iran, which were represented at the meeting.
The cultural heritage committee, formed in September 2003, aims to distribute international aid to help protect Iraq's cultural treasures.
It has received $3.5 million from direct contributions and $5.5 million from the United Nations, said UNESCO's deputy director-general for culture, Mounir Bouchenaki.
UNESCO's World Monuments Fund this week placed the entire country of Iraq on the list of the world's most endangered cultural sites. It was the first time an entire country has been listed.
By Sophie Nicholson