The president of Chad, Idriss Deby, announced on Friday that Chadian troops, who are part of a larger African force fighting in northern Mali, have killed one of al-Qaeda's leading commanders in that country.

Deby's spokesman said that he announced Abdelhamid Abou Zeid's death during a ceremony on Friday for Chadian soldiers killed in fighting in Mali. Abou Zeid is the Algerian leader of al-Qaeda in the Islamic Maghreb (AQIM).

His death, which could not immediately be verified, would be a major blow to the group and to its growing influence in North Africa.

Officials in Mali and in France, which is leading an international military intervention in Mali against fighters linked to AQIM, could not confirm reports of Abou Zeid's death.

The spokesman insisted on anonymity because he was not authorised to speak ahead of an announcement on state television on the matter. He gave no further details.

The French military moved into Mali on January 11 to push back al-Qaeda-linked fighters who had imposed strict Islamic rule in the north. They seized power there after a military coup last year, and had started moving south towards the capital, Bamako.

France is trying to rally other African troops to help in the military campaign, since Mali's military is weak and poorly-equipped. Chadian troops have offered the most robust reinforcements.

For the past 10 days, French military, along with Chadian forces, have been locked in a weeklong battle against the fighters in the Adrar des Ifoghas mountains of northern Mali, fighting which has left scores dead.

France refuses to comment

A French presidential aide said the French government would not comment on Deby's announcement.

Earlier, French president Francois Hollande said: "Information is circulating. It is not for me to confirm this, because we need to follow through the operation to the end."

French military spokesman Thierry Burkhard said on Friday night that French and Chadian soldiers are working together in a general sense but they are not always "side by side" in every operation. So he could not say whether French soldiers were involved in the operation that Deby says killed Abou Zeid.

Abou Zeid was thought to be 47 years old. He was believed to be holding four French nationals kidnapped two years ago at a uranium mine in Niger. The fate of those hostages, working for French company Areva, was unclear Friday night.

He previously kidnapped a Frenchman, released in February 2010, and another who was executed that July. He has also been linked to the execution of a British hostage in 2009.

There is uncertainty about his real name: Along with his nom de guerre, Abou Zeid had an alias, Mosab Abdelouadoud, and nicknames, the emir of the south and the little emir, due to his diminutive size.