In April United Nations Secretary-General Kofi Annan gave the International Criminal Court (ICC) a list of 51 people suspected of slaughter, rape and pillage in Darfur.
The suspects have not been named, but are believed to include top Sudanese government and army officials, militia leaders and rebel and foreign army commanders.
“The investigation will be impartial and independent, focusing on the individuals who bear the greatest criminal responsibility for crimes committed in Darfur,” the ICC said in a statement.
But the Sudanese government has rejected handing over its citizens for trial in a foreign court, saying it will prosecute war crimes suspects itself.
Khartoum says it has arrested members of the military and security forces for trial.
The UN Security Council voted in March to refer the situation in Darfur to the ICC.
The referral was made possible when Washington, which opposes the court, abstained from the vote after winning guarantees its citizens in Sudan would be exempt from prosecution.
The Darfur conflict broke after a February 2003 rebel uprising against the Arab-dominated government, accused of discrimination against non-Arabs in the region.
Sudan’s government is accused of retaliating by arming the local
Arab militia, who reportedly burned down villages and slaughtered and raped civilians, charges Khartoum denies.
At least 180,000 people have died in Darfur through violence, hunger and disease since the fighting erupted and more than 2 million have been displaced.
The US has called the violence genocide.
ICC chief prosecutor Luis Moreno-Ocampo called for cooperation from both national and international parties.
The 53-nation African Union (AU) has deployed about 2,300 troops to monitor a shaky ceasefire in Darfur, but sporadic violence continues.
Rebels have welcomed the Security Council referral and said they will hand over any of their members indicted by the ICC.
AU-mediated talks between the rebels and Khartoum are expected to resume by June 10.