THE HAGUE, Netherlands, Mar 31, 2005 (AP) -- The International Criminal Court was gearing up Thursday for a possible war crimes investigation in Sudan's violence-plagued Darfur region -- an important case that officials say could confirm the fledgling tribunal's legitimacy.

The U.N. Security Council is expected to vote Thursday on a resolution that would authorize the prosecution of Sudanese war crimes suspects by the court, whose creation was fiercely opposed by the United States.

The resolution appeared more likely to pass after U.S. officials said Washington was dropping its objections to sending the Sudan case to the court because the international pressure was too great, especially from the European countries.

The court was established in July 2002 to prosecute individual perpetrators of war crimes, crimes against humanity and genocide, but it has not yet tried a case.

Some 98 countries have ratified its founding treaty, but the United States sought to undermine its powers by signing bilateral immunity deals with countries guaranteeing they would not hand over U.S. nationals to the court.

Prosecutors said in January they would welcome the Darfur case if they were given jurisdiction by the United Nations.

Once prosecutors have jurisdiction, they would begin a preliminary analysis to determine if the crimes fall under their authority. A court official who spoke on condition on anonymity said the prosecutor would be expected to report back to the U.N. Security Council in a matter of weeks about launching a formal investigation.

A case of such magnitude would place the young institution at the center of a conflict which is estimated to have cost hundreds of thousands of lives and displaced millions more. It also would put a severe strain on its 2005 budget of around euro70 million (US$91 million).

Michael Wladimiroff, an attorney who defended the first suspect at the U.N. tribunal for the former Yugoslavia in the mid-1990s, called the apparent shift in U.S. policy an unexpected change that could open the way for further cases at the Netherlands-based court.

"This means the court ... can now be used as an instrument by the Security Council," Wladimiroff said. "All of a sudden there will be a change from waiting for cases to expanding capacity and moving more quickly toward trials."

If the United States were to drop its opposition to having cases referred by the United Nations, that would signal political acceptance of the court, albeit indirectly, he said.

The ICC is a court of last resort, empowered to step in only when countries are "unwilling or unable" to dispense justice themselves. It can only prosecute crimes if they have been committed in countries that ratified the Rome Treaty, if a nonmember country grants it special jurisdiction or if the United Nations refers a case.

Prosecutors have said they expected to issue the first arrest warrants and begin trials later this year against suspects in Uganda and Congo, but officials said they would need more money to open such a large-scale investigation.

Prosecutors are reviewing possible cases in six countries, among them Sudan, Ivory Coast and the Central African Republic. Darfur would pose a great challenge, not least because of the danger of sending investigators into a conflict zone to prepare cases and interview witnesses.

The western Sudanese region of Darfur has been the scene of perhaps the world's worst humanitarian crisis. The widespread death and destruction has been the result of a brutal counterinsurgency campaign led by government-support Arab militias against black African farmers. The conflict began in February 2003.