LAGOS, July 6 (Reuters) - Darfur's warring parties have laid the foundations for peace but rebel groups must close ranks before the next round of talks to make a full settlement possible, the talks' chief mediator said on Wednesday.

Chief mediator Salim Ahmed Salim (L) and African Union (AU) secretary general Alpha Konare (R) attend a summit on Darfur crisis in Abuja. (AFP).

A declaration of principles signed late on Tuesday by the Sudanese government and two rebel movements from Sudan's western region of Darfur goes a long way towards addressing some of the root causes of the conflict, Salim Ahmed Salim said.

"The principles elaborated in this declaration go to the very core of some of the issues we must resolve," said Salim, head of an African Union (AU) mediation team.

"Because we have done that, my belief is that it will help facilitate when we start discussion of the nitty gritty," he told Reuters in a telephone interview from the Nigerian capital Abuja, where the talks have been taking place.

The parties are due to reconvene on August 24 to tackle detailed issues and reach a final settlement.

"Hopefully the (rebel) movements will be in a better position in terms of closing their own ranks...The discussion towards the comprehensive agreement is much more complex than the discussion on the declaration of principles," said Salim.

He was not suggesting that the two movements should merge but that each one should be unified.

The Sudan Liberation Army (SLA) and smaller rebel group the Justice and Equality Movement (JEM) took up arms in early 2003 accusing the government of discrimination and neglect. They say Khartoum responded by backing Arab militias to drive non-Arabs from their villages.

The conflict has killed tens of thousands of people and driven more than two million into refugee camps.

ENDING DISCRIMINATION

The declaration of principles signed in Abuja calls for refugees to be brought home and new security arrangements.

It also sets longer-term goals such as ending discrimination based on ethnic origin or religion, sharing Sudan's wealth equitably, devolving power to the regions and recognising Darfur's tribal land ownership rights.

It took more than three weeks of negotiations to agree on the three-page document. The main difficulty was disunity within the SLA and the JEM, which meant negotiators for the movements contradicted each other and had to engage in internal debates.

Salim said he wanted the rebels to prepare for the next round by agreeing on detailed positions on all the issues.

"The parties have committed themselves to this declaration and therefore their own intentions, their own credibility will be on the line," he said.

Some rebel factions have questioned the peace process, saying they do not feel represented by negotiators in Abuja and would not feel bound by any agreement reached there.

"You are bound to find some factions who tend to disagree but I think frankly with the momentum of peace, when it is set, it will be very difficult for anyone to be a dog in the manger."