Up to 11,200 troops could be needed for a peacekeeping mission in Mali but a "parallel" military force will have to battle radical Islamists, UN leader Ban Ki-Moon said Tuesday.
The 11,200 troops would only be enough to cover main towns "assessed to be at highest risk," Ban said in a grim report on conditions in Mali that the UN Security Council will discuss Wednesday.
The UN leader said there would be a "fundamental requirement for a parallel force" in Mali and possibly neighboring countries -- in a clear signal that France will have to maintain a strong military involvement in the conflict.
The second force would "conduct major combat and counter-terrorism operations and provide specialist support beyond the scope of the United Nations mandate and capability," the UN secretary general said.
France sent troops to Mali in January to prevent an advance by Islamist forces on the capital Bamako. The Islamists and Tuareg separatists overran northern Mali one year ago, taking advantage of a vacuum left after a military coup.
Having been beaten out of Timbuktu and other Malian cities, the Islamists have retreated to desert and mountain hideouts from where they launch guerrilla attacks on French, Chadian and Malian forces.
"Terrorist groups and tactics, the proliferation of weapons, improvised explosive devices, unexploded ordnance and landmines are expected to pose significant threats" in Mali, Ban warned in his report.
France wants the 15-member council to pass a resolution in April setting up a peacekeeping force which could be in place by July.
The bulk of it would come from a West African force, known by the acronym AFISMA, which is already in Mali.
Ban said a peacekeeping force could only be deployed when the UN secretariat had decided that it would be safe enough.
He added that if the Security Council were to reject a peacekeeping force, the UN could set up an expanded political office and let AFISMA do security and peacekeeping duties outside UN control.
Ban's report and a separate document prepared by a top UN peacekeeping official portray a dark picture of the challenges ahead in Mali.
While the militant groups have gone underground, Ban's report said there was a "crisis of governance" marked by "endemic corruption" and a lack of state authority.
A political roadmap adopted by the transitional government calls for elections to be held by July 31.
But UN peacekeeping deputy chief Edmond Mulet said in a confidential report to Ban, obtained by AFP, that he thought it "unlikely" the elections could be held on time. Mulet has just returned from a mission to Mali to draft the options for the peacekeeping force.
Ban's report said that with the weak central government and no sign of reconciliation between the northern and southern halves of Mali, "elections could provoke further instability or even violence."
The UN leader added that there was a "worrying human rights situation."
Rights groups say there have been widespread reprisal killings of Tuaregs and other minorities by the Malian army as they retake northern towns.
The United Nations has also highlighted the political divisions in Bamako, which it says cloud hopes for a return to peace.
The coup one year ago was led by Captain Amadou Haya Sanogo, who handed over power to the transitional government.
But Mulet's confidential report said "Captain Sanogo and his entourage maintain a low profile, but remain influential figures with a firm hold on key ministries and continue to enjoy popular support."
"Captain Sanogo's continued presence will complicate meaningful reform," said Mulet's memorandum.