By Andrew Heavens

KHARTOUM (Reuters) - One of Darfur's strongest rebel groups on Friday said it had refused to take part in a planned peace conference in Qatar and demanded instead one-to-one negotiations with Sudan's government.

The rejection from the Justice and Equality Movement (JEM) will be seen as a setback for the Sudanese government. Sudan has held up the Qatar plans as a key part in its strategy to end the Darfur conflict, and to deflect moves to indict its president for war crimes in the region.

Suleiman Sandal, a senior JEM commander, said leaders from his group met a high-level Qatari delegation on the Sudan-Chad border on Thursday.

"We refused to take part in the proposed conference in Doha, absolutely refused it," he told Reuters by satellite phone.

"We told them the Arab League is biased in favour of Khartoum." The Arab League is spearheading plans for the talks in Doha and asked Qatar to start making plans for a conference.

Sandal said JEM also refused to share a negotiating table with any of Darfur's other armed groups, even the various wings of the influential but splintered Sudan Liberation Army (SLA).

"We should negotiate alone ... Man to man, just the two parties," he added. "We want bilateral negotiations between JEM and the Sudanese government, nobody else."

JEM is widely seen as one of the most powerful rebel forces in Darfur and launched an unprecedented military attack on Khartoum in May.

More than five years of conflict in Darfur has killed 200,000 people and driven 2.5 million from their homes, say international experts. Khartoum says the conflict has been exaggerated by the West.

The Doha plan is the latest in a series of troubled efforts to find a negotiated settlement to the conflict, which started in 2003 when mostly non-Arab rebels took up arms, accusing Khartoum of neglect.

"BOUND TO FAIL"

Sandal said any attempt to negotiate a complicated agreement between Khartoum and all of Darfur's fractured movements at once was bound to fail, as the Sudanese government would soon find ways to undermine it.

He added that other, smaller rebel groups had also been infiltrated by Sudanese intelligence and so would not negotiate in good faith.

The Arab League suggested organising its own peace effort after the chief prosecutor of the International Criminal Court asked judges to issue an arrest warrant for Sudan's President Omar Hassan al-Bashir earlier this year, accusing him of orchestrating genocide and other war crimes in the western region.

Both the Arab League and the African Union have opposed the court's move, saying it would damage chances for a negotiated peace. Sudan has stepped up diplomatic efforts to persuade members of the U.N.'s Security Council to use their powers to defer the legal move and launched a nationwide consultation to come up with its own solution to the conflict.

Sandal said JEM might still be able to work with Qatar as a mediator, as long as there was no link with the Arab League. He added his delegation was hoping to hold more talks with the Qatari delegation, which included the country's state minister for foreign affairs, in the coming days.