NATO said Wednesday that it had not been asked to assist a military alliance in resolving the armed conflict in Mali as Burkina Faso's president pushed for renewed talks between Islamist fighters and the Malian government.

According to NATO, no request was made for it to assist West African forces in retaking control of Mali's north. The organisation was responding to comments made on Tuesday by the African Union chairman, Benin's President Thomas Yayi Boni, urging NATO to intervene.

"There has been no request or discussion on a possible role for NATO in Mali," said a NATO official who asked not to be named.

"NATO is not involved in this crisis but the situation in northern Mali is of course of grave concern to us all. It threatens the security and stability of the country, the region and beyond," the NATO official said.

Later Wednesday, hundreds of demonstrators gathered on the streets of Mali's capital, Bamako, and the southwestern city of Kati, calling for the liberation of the northern part of the country and the resignation of Mali's interim president, Dioncounda Traore.

The West African nation of Mali has been cut in two since March last year, when Tuareg rebels -- including Islamist fighters -- seized control of cities in the north and east of the country.

Burkina Faso President Blaise Compaore, charged with mediating talks between rebels and the government, said Wednesday he was confident of an imminent agreement, in a New Year wishes message seen by AFP.

"As mediator in the Mali crisis, I will be inviting the transitional government, armed rebel movements and other figures to the Burkinabe capital of Ouagadougou in the coming days to continue talks and reach a framework agreement," said Compaore.

Talks initially planned between the Malian government and two of the armed groups -- Ansar Dine and the MNLA -- for this Thursday were dropped to give all parties more time to prepare.

The agreement would aim to "stop all hostilities", "respect human rights and fundamental freedoms in northern Mali" and create "an internal platform for dialogue".

In Wednesday's protests, demonstrators in Bamako lit car tyres and divided the city into two by obstructing traffic on two of the three bridges that links it over the river Niger.

In Kati, youths mounted barricades, cut off traffic and chanted slogans demanding Traore's departure.

Three Islamist movements -- the Al-Qaeda-linked Ansar Dine, the Movement for Oneness and Jihad in West Africa and Al-Qaeda in the Islamic Maghreb -- control Timbuktu, Kidal and Gao, the regional administrative centres in northern Mali.

Ansar Dine and another armed group in the north, the ethnic Tuareg and secular Azawad National Liberation Movement (MNLA), are homegrown movements.

The MNLA launched the initial offensive against forces in January 2012 but was quickly overpowered by Ansar Dine and its Islamist allies. It is unclear how much territory, if any, it now controls.

The push for talks comes as the Islamist rebels make an apparent advance towards Mopti, the gateway into government-controlled southern territory.

Mali sent extra troops to the town overnight to counter the advance, an army officer told AFP.

Residents reported seeing convoys carrying soldiers and weapons travelling during the night from Mopti, which lies about 650 kilometres (400 miles) northeast of Bamako, to the nearby town of Sevare, some 15 kilometres away.

Islamists have since retreated east of Mopti, a security source told AFP Wednesday, and relative calm returned to the area.

The Economic Community of West African States has 3,300 troops on standby for a mission to reclaim northern Mali that received the approval of the UN Security Council on December 20.

No timetable has been given for an intervention and senior UN officials have warned no deployment would take place before September.