French forces in Mali have killed Abdelhamid Abu Zeid, a leading field commander of Al-Qaeda's North Africa wing AQIM, Algerian Ennahar television reported on Thursday.

The station said 40 militants including Abu Zeid were killed in the region of Tigargara in northern Mali three days ago. A French Defense Ministry official declined to comment on the report. Algeria did not confirm the killing.

France launched a whirlwind assault to retake Mali's vast northern desert region from AQIM and other Islamist rebels on 11 January after a plea from Mali's caretaker government. The military intervention dislodged the rebels from several main towns they had occupied and drove them back into desert wilds.

AQIM, which stands for Al-Qaeda in the Islamic Maghreb, has earned tens of millions of dollars in ransom payments for Western hostages taken to its strongholds in northern Mali.

Abu Zeid has been regarded as one of AQIM's most ruthless operators. He is believed to have executed British national Edwin Dyer in 2009 and a 78-year-old Frenchman, Michel Germaneau, in 2010.

Canadian diplomat Robert Fowler, in an account of his kidnapping by another Islamist cell in the Sahara, recounted how Abou Zeid refused to give medication to two hostages suffering from dysentery, one of whom had been stung by a scorpion.