NAIROBI, Kenya -- Six months after al Qaida-affiliated militants took control of Timbuktu in northern Mali, evidence is mounting that plans for an international effort to prevent the desert region from becoming a new terrorist haven are facing steep challenges and that no military operation against the extremists is likely for a year or more.

In a report issued Wednesday to the United Nations Security Council, Secretary-General Ban Ki-moon repeatedly raised concerns about a proposed force made up of troops from West African nations and backed by Western countries.

"Fundamental questions on how the force would be led, sustained, trained, equipped and financed remain unanswered," his report said.

At the same time, the report noted, "Northern Mali is at risk of becoming a permanent haven for terrorists and organized criminal networks where people are subjected to a very strict interpretation of Shariah law and human rights are abused on a systematic basis."

Militants who belong to al Qaida in the Islamic Maghreb and other affiliated Islamist groups began seizing control of northern Mali last spring. While U.S. officials remain uncertain how serious a threat the al Qaida group is to American interests, the deaths in September of the U.S. ambassador to Libya and three other Americans heightened worries, amid Libyan government claims that Mali-based extremists had participated in the attacks on the U.S. consulate and a CIA station in Benghazi, Libya. U.S. officials have said that some of the Benghazi attackers telephoned fellow extremists in Mali to boast of the attacks.

Others have noted that the area the al Qaida-linked groups now control is the size of Texas, with airstrips and trafficking routes in the middle of a region where cross-border movement is difficult to monitor.

Still, military action appears a long way off. Last week, Moroccan news reports quoted the U.N. special envoy to Africa’s Sahel region, Romano Prodi, as saying that next September would be the earliest that any military intervention could begin. The U.N. confirmed that Prodi made the remark.

But most seem to acknowledge that even a one-year timetable for any internationally backed offensive into northern Mali would be optimistic. That leaves the militants months to prepare and recruit, and little incentive to negotiate.

"The issue with Mali is there are no good solutions," said one Western security analyst who spoke only on the condition of anonymity to protect private conversations with U.S. officials.

The U.N. report lays out the concerns that weigh against an intervention.

Under a plan developed in consultation with American and European advisers by a bloc of nations known as the Economic Community of West African States, 3,300 African troops would be sent to Mali to support a force of 5,000 Malian troops for an eventual counteroffensive in Mali’s desert north. The force would be called the African-led International Support Mission for Mali.

The U.N. report said it was unclear that the West African organization had received commitments for the 3,300 troops. "Pledges are still required," the report said.

The report also noted that the Malian troops and those from other African countries will need significant training and equipping, and that many of the African troops will be ill-prepared to operate in a desert climate. Planning is ongoing, it said, calling the proposal “a work in progress.”