KHARTOUM, Oct 14 (Reuters) - Talks to end Sudan's Darfur conflict are being stymied by fresh violence blamed on rebel factions, a political standoff in Khartoum, and deteriorating relations between Sudan and the African Union.

The much-anticipated sixth round of African Union-sponsored talks in the Nigerian capital Abuja is coming to an end but analysts say there is little to show for the weeks-long effort.

Much of the negotiation has centred around technical points rather than tangible issues of wealth and power-sharing needed to end the 2-1/2 year conflict, which has driven 2 million people from their homes.

"There is a delay now -- the armed groups and the government are not keen enough to step forwards to reach an agreement," said Faysal el-Bagir, head of the Khartoum human rights centre. He called for more international pressure on both sides.

Violence escalated as the current round of talks began in mid-September. But some say rather than jockeying for positions on the ground, this was a sign of a more sinister twist -- the splintering of rebel groups.

While the two main groups, the Justice and Equality Movement (JEM) and the Sudan Liberation Army (SLA) were talking peace at Abuja, breakaway groups were being blamed for attacks on the 6,000-strong AU force monitoring Darfur's much-violated ceasefire.

The AU suffered its first casualties in more than a year of operations last week, losing six personnel. Rebel factions also held a 38-member AU team hostage, demanding a seat at Abuja. Mainstream JEM forces secured their release.

Aid workers say negotiations to release three Sudanese aid workers kidnapped by the SLA in North Darfur two weeks ago involved new rebel interlocutors, a sign of further splits.

They say any Abuja deal will mean little on the ground if the rebels continued to factionalise.

NEW GOVERNMENT

Top U.N. envoy in Sudan Jan Pronk said the rebels needed to take control of these factions.

"The movements have to show that, in the areas which they claim to control, they take all action necessary to stop so-called split factions or dissident commanders, rather than seemingly allowing them to continue acting in violation of (agreements signed)," he said.

But other issues are slowing talks at Abuja meaning a deal may be a long way off.

The Sudan People's Liberation Movement (SPLM), which recently became partners in a new coalition government in Khartoum, are demanding a new government delegation to the Abuja talks, a fresh position and a clear road map to include them.

"The SPLM believes that the new government of national unity has to have a joint position," senior SPLM official Yasser Arman told Reuters.

The SPLM, themselves a former southern rebel group, have good relations with the Darfur rebels who have said they would welcome their involvement in negotiations.

But the SPLM says Khartoum has been reluctant to meet this demand, despite statements from senior officials that the SPLM would be included in the Abuja delegation during the current round of talks.

Khartoum has in the past accused the SPLM of supporting the Darfur rebels.

SOURING RELATIONS

Further adding to complications is a souring of relations between the government and the AU.

The AU, infuriated by the renewed clashes between rebels and government on the ground, and new attacks by Arab militias on refugee camps, voiced its harshest criticism yet of all parties earlier this month.

The head of the AU's Sudan mission, Baba Gana Kingibe, accused the government of coordinating attacks with militia, using helicopter gunships in attacks and obstructing the deployment of essential AU armoured vehicles.

The government denied the claims.

Since then, declarations that the government would cooperate with the AU have evaporated. Instead a senior Foreign Ministry official said he expected the AU to remove Kingibe from his post.

The Sudanese embassy in AU headquarters in Addis Ababa issued a sharply critical statement: "The outcome of the media statement Ambassador Kingibe has made is quite damaging to the ongoing peace process and in particular to the negotiations in Abuja," it said.

Pronk is still hopeful for a deal by the end of the year, although many feel this is optimistic.

But even if a deal is reached, he agrees it will be only a first step towards securing the remote region where violence has been increasing in recent weeks.