The UK has warned rebel groups in Darfur they could be excluded from the peace process if they boycott talks due to be held in Libya later this month.
A number of rebel movements have threatened not to attend the talks
The UK Minister for Africa, Lord Malloch Brown, said those who opted out "should understand the consequences".
The meeting was arranged so the rebels could unify their negotiating position ahead of talks with Sudan's government.
One key rebel faction says it will not enter peace talks until the promised peacekeeping force is deployed.
The Paris-based Abdul Wahid al-Nur faction of the Sudan Liberation Movement/Army told the BBC that Darfur needs the international community to live up to its responsibilities to stop the killing.
"We need action from the UN and the international community should do their responsibilities (...) and after that go to the negotiating table and we are ready to go at that time," said spokesman Yahya Bashir.
The Justice and Equality Movement, one of Darfur's main rebel factions, said the British threats were not helpful.
Haroun Abdul Hamid, a spokesman for the group, told the BBC: "I think it is better for the Africa minister to do the efforts towards helping people to make common ground towards the peace, rather than making these threats."
Meanwhile, UN officials have appealed for helicopters and trucks for the new UN-African Union mission in Darfur to replace the poorly equipped 7,000 AU observers currently deployed.
The head of UN peacekeeping operations, Jean-Marie Guehenno, said the 24 military helicopters and 60 transport vehicles the UN required would be essential for the success of the 26,000-strong force once it deploys.
Mr Guehenno said the recent rebel attack on the AU base near Haskanita in northern Darfur, and the subsequent destruction of the town by the Sudanese army, showed why having a highly mobile force was critical to stopping the violence.
Some of the largest of the more than a dozen rebel groups are threatening not to attend the peace talks due to take place in Tripoli on 27 October.
The BBC's Martin Plaut says the prospects for the meeting are now looking increasingly grim, with the level of violence in Darfur on the rise as all parties jostle for control of territory.
Lord Malloch Brown wants the rebels to unify their negotiating position
The talks have been endorsed by the UN Security Council and Lord Malloch Brown had a blunt message for those considering staying away.
"Rebel leaders that do not go are, in many ways, abdicating their right to represent people," he told the BBC.
"That means anybody who wants to be a legitimate representative of the Darfuri people needs to go there. If they opt out, they should understand the consequences of doing that - probably their role in the peace negotiations may be finished."
The Egyptian foreign minister Ahmed Aboul Gheit met representatives from the main rebel groups on Monday in an attempt to persuade them to attend the Libya talks.
A statement from the foreign ministry in Cairo said he had urged all the rebels to "halt military operations and seize the chance to prepare for the proper environment to make the negotiations successful".
The divisions among the rebel movements and their inability to find a common cause have been some of the most difficult issues for the international community to deal with, our correspondent says.
But unless all sides can be persuaded to attend there is little hope that the Libyan talks will contribute to the resolution to the crisis in Darfur, he adds.
At least 200,000 people have died in Darfur during a four-year conflict and more than two million have been forced from their homes.