The chief prosecutor at the International Criminal Court (ICC) said he has nearly completed an investigation into war crimes in Sudan's Darfur region and has sufficient evidence to file charges soon.
"Based on a careful and thorough source evaluation of all the evidence collected, we were able to identify the gravest incidents and some of those who could be considered to be the most criminally responsible," Luis Moreno-Ocampo said in a speech to the annual meeting of the court's member states.
Tens of thousands of people have been killed, and 2.5 million forced from their homes in three years of conflict in Darfur, a remote region of western Sudan where the US government says genocide is taking place. Khartoum rejects the charge.
Mr Moreno-Ocampo said the crimes committed include persecution, torture, rape and murder.
Before the prosecution submits the evidence to ICC judges, the office of the prosecutor will assess whether Sudan's government is conducting its own judicial proceedings on the same incidents and persons, Mr Moreno-Ocampo said.
Jan Egeland, the top UN humanitarian official, accused Sudan on Wednesday of deliberately hindering relief aid in Darfur, attacking villages and arming Arab militia to combat rebels and bandits.
The United Nations, Sudan and the African Union (AU), which has fielded a 7,000-member force, agreed in principle in Addis Ababa last week on a strengthened AU force with extensive UN support.
Sudan had previously ruled out a big UN role in Darfur, concerned that its forces may try to enforce ICC warrants.