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 that left 37 foreign hostages dead in January.
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 Ifogha mountains on Saturday.
There was no immediate confirmation of his death from elsewhere but US Republican Representative Ed Royce, who chairs the House Foreign Affairs Committee, hailed the reported killing.
"This would be a hard blow to the collection of jihadists operating across the region that are targeting American diplomats and energy workers," the US lawmaker said in a statement.
Belmokhtar, an Algerian national and Afghanistan veteran, had broken away from Al-Qaeda in the Islamic Maghreb (AQIM) weeks ago to form a group called Signatories in Blood.
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, a few days earlier.
A Mauritanian news agency said he was killed by a French air strike.
If the deaths 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 jihadist insurgency in Mali.
"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 attack 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.
Foreign governments were still trying to confirm that Belmokhtar's former boss in the AQIM hierarchy, Abou Zeid, was dead.
Chad's 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.
No confirmation in jihadist internet forums
Analysts have suggested Abou Zeid's death could spell AQIM's doom, with breakaway jihadist groups and other radical Islamist movements now thriving in the region. But while Washington described the report as "very credible", France has so far treated it with caution.
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.
Guidere said Abou Zeid had adopted such a hard line since reaching the top of AQIM's operational command that many of his lieutenants had left the group to join other organisations or launch their own.
Belmokhtar, also known as a smuggling baron, had previously thrived thanks to his intimate knowledge of the nearly lawless "Grey Zone" of southern Algeria, northern Mali and neighbouring Niger. That success was strengthened by a network of tribal alliances that he cemented through marriage.