* Security Council wants details on planned intervention
* France drafts resolution to 'energize' African response
By Michelle Nichols
UNITED NATIONS, Oct 4 (Reuters) - U.N. political affairs chief Jeffrey Feltman told a closed Security Council meeting on Thursday that Mali urgently needed international help to reclaim the north of the country from Islamist militants and that "time is not on our side," U.N envoys said.
Mali descended into chaos in March when soldiers toppled the president, leaving a power vacuum that enabled Tuareg rebels to seize two-thirds of the country. But Islamist extremists, some al Qaeda allies, hijacked the revolt in the north.
Feltman told the council the situation in the north of Mali continued to deteriorate, posed a "genuine threat" to regional peace and security, and that the international community urgently needed to deliver a unified response, said council diplomats.
West Africa's regional body, ECOWAS, has mapped out a three- phase operation to help Malian troops recapture the north, and Mali's interim leader, Dioncounda Traore, asked the 15-member U.N. Security Council earlier this month to authorize the force.
"Mali would appreciate the immediate presence of such a force in order to support Mali's defense and security forces in exercising their sovereign missions of regaining control, preserving territorial integrity and protecting persons and property," Traore said in the letter released on Thursday.
The African Union asked the Security Council in June to support a military intervention in Mali, but the council said it needed to clearly spell out the aims of such an operation and how it would be carried out.
A senior Western diplomat, who did not want to be identified, said the plan was still lacking enough detail for the council to act.
"It's difficult for the Security Council to authorize military intervention when we don't have a concept of what that means and who's going to do it and what the purpose of it is," he said, speaking on the condition of anonymity.
Deputy U.N. Secretary-General Jan Eliasson said the African Union was also not united on the issue. "It's not a very clear situation ... so many unknowns," he told reporters.
Mali's neighbor, Algeria, opposed any military intervention, the senior diplomat said, because it was worried al Qaeda would flee northern Mali to Algeria.
French U.N. Ambassador Gerard Araud said on Thursday that he would shortly circulate a resolution to energize the African response. It would not yet authorize a military intervention by an international force, but would instead set a deadline for ECOWAS and the African Union to provide the Security Council with details of the operation.
"We need as soon as possible a concept of operation accepted by Mali and by the ECOWAS members," he said. "Everybody knows that there are divisions, there are disagreements, so as the Security Council we are trying to build the momentum, which it has so far been lacking."
Araud said the African Union, ECOWAS, the United Nations and others were due to meet in Bamako on Oct. 19 to discuss the way forward and it was hoped that the U.N. Security Council might afterward be able to authorize a military intervention.
ECOWAS has intervened militarily in past African conflicts, including the wars in Liberia and Sierra Leone.
The conflict in Mali has also exacerbated a deteriorating humanitarian and security situation in the turbulent Sahel region - a belt of land spanning nearly a dozen of the world's poorest countries on the southern rim of the Sahara - where millions are on the brink of starvation due to drought.
The United Nations is considering appointing a special envoy on the Sahel, and U.N. diplomats said possible candidates who had been suggested included former Nigerian President Olusegun Obasanjo, former Gabon Foreign Minister Jean Ping, U.N. special envoy for West Africa Said Djinnit of Algeria, and former Syria mediator and former U.N. Secretary-General Kofi Annan. (Additional reporting by Louis Charbonneau; Editing by Peter Cooney)