The Hague, Netherlands ? The International Criminal Court said Monday it had begun investigating war crime allegations in Sudan’s Darfur region, where an estimated 180,000 people have died and 2 million have been displaced since the conflict began in 2003.

The court has a list of 51 potential suspects named by a special U.N. investigative commission, which concluded in January that crimes against humanity had occurred in Darfur.

The government in Khartoum, accused of trying to intimidate international aid workers, indicated it would not cooperate with the world’s first permanent war crimes tribunal or allow its citizens to be sent abroad for trial.

The U.N. Security Council asked the court to take on the Darfur situation two months ago, in what would be the first case to be investigated against the will of the country where the alleged crimes took place. The court also is investigating war crimes in Congo and Uganda.

A failure by Khartoum to cooperate with the court could result in economic sanctions, human rights groups said.

The investigation is the court’s most difficult and dangerous so far as it ventures into the vast desert of western Sudan.

Prosecutors said their work will be “impartial and independent, focusing on the individuals who bear the greatest criminal responsibility for crimes committed in Darfur.” Initial inquiries have been made with dozens of experts, resulting in thousands of pages of case material, they said.

Chief Prosecutor Luis Moreno-Ocampo also appealed to “all partners to provide his office with the information, evidence and practical support needed to carry out his mandate.”

Darfur’s crisis erupted when rebels took up arms because of what they considered years of state neglect and discrimination against Sudanese of African origin. The government is accused of responding with a counterinsurgency campaign in which the ethnic Arab militia known as the Janjaweed have committed wide-scale abuses against ethnic Africans.

A U.N. special International Commission of Inquiry on Darfur concluded in January that crimes against humanity had occurred in Darfur, although it said the mass killings fell short of a policy of genocide. It recommended that the case go to the fledgling court in The Hague.