Fears mounted Thursday that Al Qaeda-linked Islamists were turning Mali into a rogue state despite the announcement by Tuareg rebels that their 10-week military offensive was complete.

As the Tuareg trumpeted the success of a decades-old struggle to "liberate" their homeland, their fundamentalist comrades-turned-rivals began imposing sharia in northern Mali, also leaving an embattled junta looking very vulnerable in Bamako.

The UN Security Council on Wednesday called for an immediate ceasefire but proposed no firm action to reverse a sequence that has seen a country hailed as a democratic success story descend into chaos in barely two weeks.

The United States, which had grown increasingly concerned since the collapse of Moamer Kadhafi's Libya scattered weapons across the region, engaged talks with Algeria, the most powerful of Mali's seven neighbours.

Algerian President Abdelaziz Bouteflika met General Carter Ham, who heads the US Command for Africa (AFRICOM) in Algiers on Wednesday.

They had in-depth talks on the security situation in Mali, Carter told the Algerian news agency.

Military cooperation and anti-terrorism coordination were also discussed during the talks, attended by several other top officials from both sides, including Washington's top Africa diplomat Johnnie Carson.

Three of Al Qaeda in the Islamic Maghreb's (AQIM) top leaders, all of them Algerians, were spotted in the Malian city of Timbuktu in talks with Iyad Ag Ghaly, a former Tuareg rebel who recently founded the Islamist group Ansar Dine.

The group, whose name means "Defenders of Faith" in Arabic, has ordered women to wear headscarves and threatened to cut off the hands of thieves in the city, once known as the "pearl of the desert" and once the jewel in Mali's burgeoning tourism industry.

The junta in Bamako and local residents have alleged that women were being kidnapped and raped by the city's new masters.

Former colonial power France has voiced fears that while the Tuaregs' territorial claims could be addressed through negotiation, the Islamist advance is a threat to the entire region.

Residents and security sources said the Islamists have chased the Tuareg group Azawad National Liberation Movement (MNLA) out of Timbuktu, burning their flag and replacing it with their black jihad flag.

"Ansar Dine has allowed MNLA elements to stay behind at the airport" just outside the town, a security source said. A hotelier said there were less than 20 Tuareg rebels stationed there.

But on their website, the group said it was "holding its position in the face of all these mafia networks and distances itself from Ansar Dine and others who rise up on the path to the liberation of Azawad".

The UN hammered out a joint statement Wednesday calling for an immediate ceasefire in Mali, prompting the MNLA to declare an end to military operations "after the complete liberation of the Azawad territory".

The world body also condemned the coup by a group of low-ranking army officers who took control of the capital Bamako on March 22 and ousted President Amadou Toumani Toure just weeks before he was due to step down.

The junta, which came to power in what some observers have described as "an accidental coup", was struggling to assert its authority.

The new military rulers' efforts to restore order fell apart as a coalition of some 50 political parties and 100 civil society organisations refused to take part in a proposed national meeting on the country's future.

The junta, which had planned the meeting for Thursday, was quickly forced to postpone it.

The mutineers had justified their coup by arguing that Toure's regime had failed to effectively tackle the Tuareg uprising but the rebels have since then conquered a chunk of territory larger than France virtually unopposed.

In an interview with the French dailies Le Monde and Liberation published Thursday, coup leader begged Western powers to help him counter the Islamist push in the north.

"If the great powers are able to cross oceans to battle fundamentalist structures in Afghanistan, what's stopping them coming to us? Our committee wants the best for the country," he said.

The crisis precipitated by Sanogo's coup also sparked mounting concern that a massive regional humanitarian emergency fueled by conflict and drought was developing.

More than 200,000 people have been forced from their homes since the Tuareg rebels launched their offensive on January 17.