By Gus Trompiz and Joe Penney
PARIS/GAO, Mali (Reuters) - France said on Sunday a third French soldier had been killed fighting Islamist rebels in Mali and reiterated that it could not confirm Chad's report that its own troops had killed the al Qaeda commander behind January's mass hostage-taking in Algeria.
A whirlwind seven-week campaign has driven al Qaeda-linked fighters who took over northern Mali last April into mountain and desert redoubts, where they are being hunted by hundreds of French, Chadian and Malian troops.
France's defense ministry said 26-year-old Corporal Cedric Charenton was shot dead on Saturday during an assault on an Islamist hideout in the Adrar des Ifoghas mountains near Algeria, the third French soldier killed in the campaign.
French army spokesman Colonel Thierry Burkhard said some 15 Islamists were killed there but that he could not confirm Chad's report that Chadian troops had killed al Qaeda regional leader Mokhtar Belmokhtar at another camp in the Adrar des Ifoghas.
"We are facing a very fanatical adversary," Burkhard said, noting the Islamists were armed with rocket- and grenade-launchers as well as machine guns, AK47 assault rifles and heavy weapons. "They are fighting without giving ground."
The death of Belmokhtar, nicknamed 'the uncatchable', has been reported several times in the past. The latest came a day after Chadian President Idriss Deby said Chadian forces had also killed Adelhamid Abou Zeid, al Qaeda's other senior field commander in the Sahara.
The killing of Belmokhtar and Abou Zeid, if confirmed, would eliminate all Qaeda's leadership in Mali and raise questions over the fate of seven French hostages thought to be held by the group in northern Mali, an area the size of Texas.
Al Qaeda in the Islamic Maghreb (AQIM) has pledged to avenge the French assault on its fighters in Mali, which Paris said it launched due to fears its former colony could become a launchpad for wider al Qaeda attacks.
Belmokhtar, whose smuggling activities the Sahara earned him the nickname "Mr Marlboro", became one of the world's most wanted jihadis after masterminding the raid on the In Amenas gas plant in Algeria in which more than 60 people were killed, including dozens of foreign hostages.
Abou Zeid is regarded as one of AQIM's most ruthless operators, responsible for the kidnapping of more than 20 Western hostages since 2008. He is believed to have executed British hostage Edwin Dyer in 2009 and 78-year-old Frenchman Michel Germaneau in 2010.
France and Mali have said they could not confirm his death.
French radio RFI and Algerian daily El Khabar have reported that DNA tests were being conducted on members of Abou Zeid's family to confirm whether a body recovered after fighting in Adrar des Ifoghas was indeed the Islamist leader.
Mali's army, meanwhile, said it had killed 52 Islamist rebels in desert fighting some 70 km (45 miles) east of Gao, northern Mali's largest town, with support from French helicopters and ground troops.
"There was a big fight with lots of enemy killed," said Lieutenant Colonel Nema Sagara, the Malian army's deputy commander in Gao. "Our troops went out to battle and they met them. There are no dead on the Malian side."
(Additional reporting by Catherine Bremer in Paris; writing by Daniel Flynn; editing by Philippa Fletcher)
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