In a letter to Bush dated Monday, Martin Sullivan said he was resigning as chairman of the President's Advisory Committee on Cultural Property, a position he had held since 1995.

"The reports in recent days about the looting of Iraq's National Museum of Antiquities and the destruction of countless artifacts that document the cradle of Western civilization have troubled me deeply, a feeling that is shared by many other Americans," he wrote.

Calling the looting a "tragedy," Sullivan said that it was not prevented "due to our nation's inaction."

Baghdad's museum, which housed one of the world's great collections of artifacts from early Mesopotamian civilizations, was ransacked by looters on Friday in the upheaval following US troops' entry into the city.

A source close to the advisory committee told AFP on condition of anonymity that two other members, Gary Vikan and Richard Lanier, were also quitting.

Sullivan is executive director of the Historic Saint Mary's City Commission, dedicated to one of the first British colonies, in the state of Maryland. Vikan is director of the Walters Art Gallery in Baltimore, Maryland.

Lanier is director of the Trust for Mutual Understanding in New York.

The 11-member committee is made up of experts and professionals in the art world who are appointed to three-year terms.

Two are museum representatives, two are experts in archaeology and ethnology, three are specialists in worldwide art trade and four others are designated based on their areas of expertise.

Defense Secretary Donald Rumsfeld said Tuesday that the United States was offering rewards for the return of items from the museum, or assistance in their recovery.

But critics have faulted US forces for failing to intervene in the extensive pillaging of the capital and other Iraqi cities after President Saddam Hussein's regime collapsed.

Likening the looting to a post-football game riot, Rumsfeld said Tuesday: "No one likes it. No one allows it. It happens and it is unfortunate, and to the extent it can be stopped, it should be stopped."

"To the extent it happens in a war zone, it's difficult to stop," he added.

SPACE.WIRE