An Al Qaeda source has confirmed the death in Mali of Abdelhamid Abou Zeid, one of the leaders of Aqim, (al Qaeda in the Islamic Maghreb).
An Aqim militant told the private Mauritanian news agency that he was killed in a French bombing raid last week in the Ifoghas mountains.
The same source insisted however, that another Islamist leader, Mokhtar Belmokhtar, thought to have masterminded the January hostage operation in the Algerian gas plant, was still alive and fighting.
Radio France Internationale's special envoy in Mali went to Tessalit in the north east on Sunday, where he was shown photographs by a Chadian soldier, showing a blood-drenched body which the soldier declares is the corpse of Mokhtar Belmokhtar.
The Chadian soldiers say they killed Belmokhtar on Saturday in the Ametetai Valley.
French Defence Minister Jean-Yves Le Drian announced on French television on Tuesday the death of around 15 Islamist militants after heavy fighting with French and Chadian forces overnight in northeastern Mali
And on Tuesday Admiral Edouard Guillaud told journalists that the French intervention which was launched in January was breaking the back of Aqim and its allies in Mali.
However, the relatives of French hostages being held in the Sahel region are concerned for the safety of their loved ones.
They fear that they could be used as human shields or be executed as reprisal for the deaths of islamist fighters.
Pascale Robert, the grandmother of Pierre Legrand, one of the four French nationals who were seized in Niger, has called on French president François Hollande to declare a "pause in the conflict to allow for talks with the remaining figures".
French Defence Minister Jean-Yves Le Drian said on Monday that there was "every reason to believe" the hostages were still alive.