Chad says its troops in northern Mali have killed Mokhtar Belmokhtar, the one-eyed Islamist leader who masterminded an assault on an Algerian gas plant in January that left 37 foreign hostages dead.
The announcement came amid continued fighting in the mountains of northern Mali, where France on Sunday said a third French soldier had been killed since it launched operations against Islamist rebels in mid-January.
The reported death of Belmokhtar was the second time Chad said it had killed a leading Islamist militant in Mali in recent days -- after the reported death of Al-Qaeda in the Islamic Maghreb (AQIM) commander Abdelhamid Abou Zeid.
There has been no confirmation of the deaths from other governments or Islamist sources.
If the killings are confirmed, the French-led military coalition fighting in northern Mali will have eliminated the Sahel region's two historical Al-Qaeda leaders and decapitated the Islamist insurgency in Mali.
"If this information is confirmed it's a very important blow by France, because these were the two men who ran the (Islamist) organisation in the Sahel," said Anne Giudicelli, a specialist on Islamic militant groups.
France meanwhile said a soldier from the First Parachute Chasseur Regiment was killed in fighting in Mali's northern mountains on Saturday night.
The army said he was killed during an operation that also "neutralised" at least 15 Islamist rebels.
France has so far suffered relatively few casualties during its operations in Mali, launched on January 11 to back up Malian forces against Islamist rebels who seized control of the country's vast desert north last year.
A legionnaire with the 2nd Foreign Parachute Regiment was killed amid heavy clashes on February 19 and a helicopter pilot died at the very start of the operation.
The Chadian army, whose troops have been at the forefront of the hunt for Al-Qaeda-linked fighters hiding in northern Mali, said Belmokhtar was killed during an operation in the Ifoghas mountains on Saturday.
Belmokhtar, an Algerian national and Afghanistan veteran, had broken away from AQIM weeks ago to form a group called Signatories in Blood.
"The Chadian forces in Mali completely destroyed the main jihadist base in Adrar of the Ifoghas mountains" at 1200 GMT, an army statement said, adding that several militants were killed "including leader Mokhtar Belmokhtar".
Belmokhtar, 40, was seen several times in the main northern Malian cities of Timbuktu and Gao after AQIM and its allies took over northern Mali in April 2012.
He quit AQIM last year and in December the creation of his new group was announced.
In January, days after France's surprise decision to send in fighter jets and troops to help the Malian government reconquer the north, Belmokhtar claimed the attack on the In Amenas gas plant in southern Algeria.
The spectacular assault on the isolated facility, which was jointly operated by British, US and Norwegian oil companies, ended in a bloodbath, with 38 hostages killed by the time an Algerian raid ended the crisis.
Among the victims were 37 foreigners, from nations including Britain, Norway and Japan.
The report of the death of the man branded "The Uncatchable" came after Chadian President Idriss Deby Itno announced Friday that his forces had killed Abou Zeid, the top AQIM commander in Mali.
Deby said his troops killed Abou Zeid during a major battle on February 22 that also left 26 Chadian soldiers dead.
But the private Mauritanian news agency Sahara Medias had a different story. It said Abou Zeid, 46, one of the most wanted men in Africa, was killed "four days ago" in a French air strike during a clash between a unit he was leading and the Chadian platoon that had suffered the 26 losses days earlier.
Sahara Medias said the strike occurred in the mountainous region of Tigharghar near the border with Algeria and added that "extremely well-informed sources" had confirmed Abou Zeid's killing.
Algeria's El Khabar newspaper said Saturday that Algerian security services, who were the first to report Abou Zeid's death, had found his personal weapon and examined a body believed to be his.
"Confirmation of Abou Zeid's death remains linked to the results of DNA tests done on Thursday by Algeria on two members of his family," it said.
Abou Zeid was believed to be holding a number of Western hostages, including four French citizens kidnapped in Niger in 2010.
He and Belmokhtar were directly involved in most of the kidnappings of foreigners that have plagued the region in recent years.