The UN Security Council is expected to vote on Thursday on a resolution that would authorise the prosecution of Sudanese war crimes suspects by the court, whose creation was fiercely opposed by the United States.
The resolution appeared likelier to pass after US officials said Washington was dropping objections to sending the Sudan case to the court because 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.
Ninety-eight countries have ratified its founding treaty, but the US sought to undermine its powers by signing bilateral immunity deals with countries guaranteeing they would not hand over US nationals to the court.
Prosecutors said in January that 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 whether the crimes fall under their authority. A court official said the prosecutor would be expected to report back to the UN Security Council in weeks about launching a formal investigation.
A case of such magnitude would place the young institution at the centre of a conflict that is estimated to have cost hundreds of thousands of lives and displaced millions more.
It also would put a strain on its 2005 budget of around $91 million. Prosecutors have said they expect to issue the first arrest warrants and begin trials later this year against suspects in Uganda and Congo, but officials say 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.