Jan Eliasson, the UN's special envoy to Sudan, said it was crucial to capitalise rapidly on Tuesday's Security Council decision to deploy 26,000 peacekeepers in Darfur to boost the political process.
"I fear a very dangerous situation in the camps" of displaced people if there is no rapid progress on the political front, he said.
"It will take some time before all the peacekeepers are deployed. The political process is now at a crucial stage."
When the deadly conflict erupted in Darfur four and a half years ago, the uprising against the central authority in Khartoum was spearheaded by one group.
Now diplomats face the daunting task of finding common ground for a dozen rebel factions.
The talks were due to begin at 1400 GMT. However, Abdel Wahid Mohammed Nur, the Sudan Liberation Movement's founding father and a member of Darfur's largest tribe, is not scheduled to attend.
"Genocide is a crime against humanity as a whole, not just against it's immediate targets. It therefore falls on the world at large to act."
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"We regret that Abdel Wahid Nur is not here. We hope that with this decision, he is not excluding himself from the final negotiations we are planning," Eliasson said.
The absence of Suleiman Jamous, a key rebel figure who has acted as co-ordinator to facilitate the delivery of humanitarian aid to the population of Darfur, also overshadowed the Arusha talks.
Jamous was initially detained by Minawi over his opposition to the Abuja deal and has been confined to a hospital for more than a year.
Nur's faction contests the legitimacy of the many splinter groups and also argues that talks with the government should only be considered once the new "hybrid force" of UN and AU peacekeepers is deployed.
Yahia Bolad, Nur's spokesman, said: "The more you recognise individuals as faction leaders by inviting them to talks like those in Arusha, the more factions there will be, and consequently disorder on the ground."
New peace deal
A Darfur peace deal was reached with the Sudanese government in Abuja, the capital of Nigeria, in May 2006.
But it was only endorsed by one of three Sudanese groups involved in negotiations.
|The deployment of 26,000 peacekeepers in |
Darfur may help the political process [AFP]
Violence has since spiralled and splinter factions have flourished.
In mid-July, however, the leaders of five Sudanese groups gathered in Asmara, the Eritrean capital, and agreed to form an alliance, the United Front for Liberation and Development, and invited other splinter groups to join.
Four groups - including the Justice and Equality Movement (JEM) - have adopted a common position in advance of Arusha during a meeting Tuesday in Tripoli, the capital of Libya.
Ahmed Hussein Adam, JEM spokesman, said: "We reach an important time now... We welcomed the resolution on peacekeeping. Despite its shortcomings, it has opened the door for a new political process.
"In Arusha, we are going to see how we can share this new process, for it to be meaningful, comprehensive and inclusive.
"On the real issues, I don't see any differences between the various groups."