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.