Mauritanian President Mohamed Ould Abdel Aziz, who has opposed sending troops to combat Islamists in northern Mali, said Monday he would not rule out contributing to a UN force if the situation improves.

"If the situation changes... there will be nothing preventing Mauritania, as a UN member, from sending troops to the north (of Mali) or in the country's western regions to provide stability and security," he said at a press conference.

"We will take on this responsibility as soon as possible," he said, speaking at a joint event with his Niger counterpart Mahamadou Issoufou.

Abdel Aziz explained that Mauritania, one of the countries in the region with the best knowledge of Al-Qaeda groups, had not sent fighting units to support the ongoing French-led effort because it was not ready.

Former colonial power France on January 11 sent fighter jets and troops to Mali to prevent hardline Islamist groups who had occupied northern Mali since last April from gaining further ground and threatening the capital.

"It was a reaction to the catastrophic situation Mali was experiencing, it was not scheduled, it was a reaction to save a country that was going to be completely taken over by terrorists," the Mauritanian president said.

Several members of the regional bloc ECOWAS have volunteered hundreds of troops to take part in a military force to support the embattled transitional government in Bamako.

But few of them have been actively involved alongside France on the frontlines of the nearly two-month-old operation with the exception of Chad, whose seasoned desert fighters have spearheaded the hunt for militants.

Abdel Aziz stressed his country had already played "a very important part" in the military offensive by monitoring Mauritania's border with Mali, blocking supply lines and escape routes for Islamist forces.

The United Nations has barely begun looking into the feasibility of a UN peacekeeping force in Mali and France has warned any deployment was still months away.