''The US is not and will not be part of the ICC,'' said Pierre Prosper, the State Department's ambassador at large for war crimes issues, told reporters in New York.

April 11 is the date set by the UN and court supporters for when the 60th country will ratify the treaty - the number needed to establish the court. To date, 139 nations have signed the treaty; 56 have ratified the treaty and at least nine more are expected to sign it.

Prosper said that ''unsigning'' the treaty was one of several options being considered by Washington as an indication that it was not bound by the treaty. Typically, when a country signs a treaty, it then submits it for ratification by its lawmakers, something the Bush administration has vowed not to do.

The Clinton administration, after months of opposition, signed the treaty just minutes before a Dec. 31, 2000, deadline. It signed with the understanding that the treaty would be changed before congressional ratification, an unlikely prospect because of strong opposition to the court by Senator Jesse Helms, the Republican of North Carolina who chairs the Senate Foreign Relations Committee.

Prosper said too many doubts about the treaty remain. Among administration officials' concerns is that there are inadequate safeguards to protect US soldiers based abroad from politically motivated prosecutions.

The permanent international criminal court, the dream of human rights advocates since the Nuremberg war crimes trials after World War II, is intended to prosecute future cases involving war crimes. The court would step in to do so only when countries themselves fail to hold criminals accountable.

Yesterday, proponents of the court said they would push ahead with or without American support. The court, which will be based in The Hague, is expected to take effect July 1.

''The world is about to show themselves and the US they can start a major organization without US political and financial leadership,'' said William Pace, the head of the International Coalition for a permanent International Criminal Court.

Many countries that have supported the US war on terrorism see the court as a forum in which to address war crimes. They are concerned that the Bush administration might try to undermine the court.

''That would be worrying,'' said one European diplomat.

British Foreign Minister Jack Straw, in conversations with US Secretary of State Colin Powell, has encouraged the United States not to make a big issue over the differences between the two countries.

Some legal specialists said yesterday that ''unsigning'' could mean that the Bush administration will simply state its opposition in writing to the treaty and announce it will not submit it for ratification.

Palitha Kohona, head of the UN treaty section, said he knew of ''no precedent'' for a country removing its signature. It is not unusual for countries to sign and then not ratify a treaty, he said, or to take a long time to ratify a treaty. The United States, for example, signed the Genocide Convention in 1948 but did not ratify it until 1988.

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