N'DJAMENA, Chad (AFP) - Chad has said its troops in northern Mali killed 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 Mokhtar Belmokhtar was killed during an operation in the Ifogha mountains on Saturday.

The Algerian national, a ruthless 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 on 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", 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 Britain, Norway, Japan and other nations.

No other source has yet confirmed Belmokhtar's death, and foreign governments were still trying to confirm that Belmokhtar's former boss in the AQIM hierarchy, Abou Zeid, was indeed dead.