THE HAGUE, Netherlands - The International Criminal Court issued its first arrest warrants yesterday in the murderous Darfur conflict, seeking to try a government minister and a Janjaweed militia leader on charges of mass slayings, rape and torture. Sudan immediately refused to arrest them.

After studying prosecution evidence for two months, a three-judge panel decided to seek the arrests rather than to summon the suspects to surrender, saying the evidence supported 51 charges of war crimes and crimes against humanity.

The warrants against Sudan's humanitarian-affairs minister, Ahmed Muhammed Harun, and the Janjaweed militia's "colonel of colonels," Ali Kushayb, could be a crucial step toward bringing alleged ringleaders in Sudan to international justice.

Richard Dicker of New York-based Human Rights Watch said it signaled "the days of absolute impunity . . . for horrible crimes in Darfur are winding down."

Sudan was defiant. "Our position is very, very clear - the ICC cannot assume any jurisdiction to judge any Sudanese outside the country," Justice Minister Mohamed Ali al-Mardi told the Associated Press in Sudan's capital. "Whatever the ICC does is totally unrealistic."

Sudan was not party to the Rome convention that set up the court, he said, implying that it was not obliged to implement its warrants.

Asked if Sudan would continue its sporadic cooperation with the court, Mardi answered: "What cooperation? It's over."

The court's chief prosecutor, Luis Moreno-Ocampo, said Sudan was legally bound to arrest the men.

In February, Moreno-Ocampo named Harun and Kushayb as suspects in the murder, rape, torture and persecution of civilians in Darfur.

Moreno-Ocampo said the arrest warrants underscored the strength of his case, built during a 20-month probe, even though the treacherous security situation kept him from sending investigators into Darfur.

Harun is currently in the Sudanese capital, Khartoum.

Mardi has said a Sudanese investigation into Harun's activities found "not a speck of evidence" against him. The Sudanese government says it has arrested Kushayb pending an internal investigation; several witnesses said he was moving freely in Darfur under police protection.

Dicker, of Human Rights Watch, said the international community must press Sudan to arrest the men and send them to the Hague.

Failure to do so "risks furthering Sudan's isolation on the international stage," he said, noting the 2005 U.N. Security Council resolution that authorized the Darfur investigation calls on Khartoum to cooperate fully with the court and the prosecutor.

However, getting the suspects to the court, which has no police force of its own, "won't be simple, won't be quick," he said.

Dicker called on China, a permanent Security Council member, "to use its considerable influence to persuade the Sudanese leadership to cooperate."

Amnesty International suggested U.N. forces already in the country could detain them. The United Nations has a mission in southern Sudan following a peace treaty in an unrelated north-south war. But Sudan has so far resisted a large U.N. deployment in Darfur, where an undermanned, under-equipped African Union peacekeeping force is struggling.

The Darfur atrocities allegedly were committed in four towns and villages in West Darfur between August 2003 and March 2004.

Harun and Kushayb were part of a conspiracy to stamp out support for rebels by "indiscriminate attacks against the civilian population, murder, rape, inhumane acts . . . ," according to a 94-page prosecution document sent to judges in February.