By Evelyn Leopold

UNITED NATIONS, Sept 18 (Reuters) - U.N. Secretary-General Ban Ki-moon disclosed on Tuesday he had raised with Sudan's president the Khartoum government's refusal to hand over two suspected Darfur war criminals to an international court.

"I raised this issue with President (Omar Hassan) Bashir more than once in a private conversation," Ban, who visited Sudan earlier this month, told a news conference.

"As my meeting was done in private conversation, I should prefer not to disclose all the details," he said. "But ... I will continue to raise and discuss this matter."

The Hague-based International Criminal Court in May charged Ahmad Harun with organizing, funding and arming militia to stop rebels from attacking the Sudanese army. The militia then wiped out villages and are now fighting each other over the spoils.

Harun is now the minister of state for humanitarian affairs, which ICC prosecutor Luis Moreno-Ocampo says is akin to putting the man in charge of a crisis he helped foment.

An estimated 200,000 people have died and 2.5 million have lost their homes since violence broke out four years ago.

The court also issued an arrest warrant for pro-government militia leader Ali Mohammed Ali Abdalrahman, also known as Ali Kushayb, who like Harun was charged with war crimes and crimes against humanity.

But Bashir has refused to arrest them, saying the charges against Harun are false and that Sudan is not a signatory to the court.

While U.N. bodies are demanding Khartoum make the arrests, they need Bashir's agreement for a new peacekeeping force of 26,000 troops and police and Sudan's cooperation for a peace settlement in Darfur.

Recognizing the contradiction, Ban said that while justice was part of the peace process one had to keep a low profile in dealing with Khartoum.

"For a certain period, certain occasions, there are certain issues which need to be kept confidential for the purpose of promoting and making progress on those issues," Ban said.

CEASE-FIRE URGED

The Darfur crisis will be discussed at one of a series of high-level meetings Ban has arranged this week before world leaders address the U.N. General Assembly on Tuesday. Others include weekend sessions on how the United Nations can help Iraq and Afghanistan, a Middle East mediators meeting and a climate change summit on Monday.

Ban in his comments said he also urged Bashir work towards a cease-fire in Darfur, particularly in light of a recent increase in fighting.

"For that, he must commit to this cessation of hostilities and protect all humanitarian workers and humanitarian assistance should be flowing without any hindrance and protect and respect human rights."

"These are what I have emphasized. I was very much concerned about all this recurrence of violence."

Asked whether he had contacted the Sudanese president about the attacks, which broke out after his recent visit. he said he had not "but I hope that he has heard my statement and my concern clearly."

Ban on Monday warned that the recent fighting in Sudan's Darfur region could derail peace talks among rebels and the government that he had announced would start in Libya next month.

His statement focused on incidents in Haskanita in North Darfur, on Sept. 10 and 11, when African Union peacekeepers said government aerial bombardments involving helicopter gunships and ground clashes had killed a number of civilians.

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