Mokhtar Belmokhtar, the one-eyed Islamist reported Monday to have been killed in a US airstrike in Libya, was an Al-Qaeda veteran and mastermind of a devastating attack on an Algerian gas plant.

Branded "the Uncatchable", he was twice condemned to death by Algeria and reported killed in Mali at least once before the US -- which had placed a $5 million bounty on his head -- targeted him.

Of all the jihadis in Africa's Sahel region, it is Belmokhtar whose image hangs in the office of Colonel Luc Laine, the French army head in Gao, northern Mali -- "to remind myself that he exists, and that he wants to hurt me", the officer recently told AFP.

As well as the gas plant siege in 2013, Belmokhtar personally supervised plans for twin car bombings in Niger that killed at least 20 people that year, according to a spokesman for his group.

Belmokhtar was born in 1972 in the Algerian desert city of Ghardaia.

In a rare 2007 interview, he said he was fascinated by the exploits of the mujahedeen fighting the Soviet invaders of Afghanistan, and joined them in 1991 when he was barely 19.

It was in Afghanistan that he said he lost an eye to shrapnel, and where he had his first contact with Al-Qaeda.

He returned to Algeria in 1993, a year after the government sparked civil war by cancelling an election the Islamic Salvation Front was poised to win.

- Split with Al-Qaeda -

He joined the Armed Islamic Group (GIA), which waged a campaign of civilian massacres, sometimes wiping out entire villages.

Belmokhtar thrived thanks to his knowledge of the nearly lawless "Grey Zone" of southern Algeria, northern Mali and neighbouring Niger, and a network of tribal alliances he cemented through marriage.

In 1998, the Salafist Group for Preaching and Combat (GSPC) broke away from the GIA. Belmokhtar, now nicknamed "The Uncatchable" by a former French intelligence chief, went with them.

Nine years later, the GSPC formally adopted the jihadist ideology of Osama bin Laden, renaming itself Al-Qaeda in the Islamic Maghreb.

AQIM spun a tight network across tribal and business lines in the Sahel, comfortable operating in harsh desert terrain and making millions of dollars from ransoming European hostages.

But Belmokhtar was ousted as one of AQIM's top two leaders in northern Mali for what one regional security official said were his "continued divisive activities despite several warnings".

With a reputation for smuggling -- dealing in contraband cigarettes, stolen cars and even drugs, as well as profiting from illegal immigration networks -- Belmokhtar's commitment to AQIM's puritanical brand of Islam was questioned by some.

A Malian official said AQIM supremo Abdelmalek Droukdel claimed Belmokhtar had been "dismissed for straying from the right path".

The split made international headlines in 2013 after a scathing letter from Al-Qaeda to Belmokhtar was found and published following the French intervention in Mali.

- Signatories in Blood -

Belmokhtar then founded Signatories in Blood in late 2012 and later merged it with MUJAO, one of the jihadist groups that seized control of northern Mali in early 2012, to form the Al-Murabitoun group.

He launched the Algerian gas plant attack days after France led an armed intervention into Mali in January 2013, which his group termed a "Crusader campaign".

The four-day siege at the In Amenas plant left 38 hostages, all but one foreign, dead. Twenty-nine militants were also killed.

Chad had claimed that Belmokhtar was killed in northern Mali in 2013, but France never confirmed his death and three months later Washington placed a $5-million bounty on his head.

Al-Murabitoun claimed responsibility for the first ever attack against Westerners in Bamako on March 7.

Three Malians, a French national and a Belgian were killed when militants stormed a nightclub popular with the capital's expatriate community.

The group said it was avenging a jihadist killed by the French army in December 2014 in northern Mali, and punishing the West for mocking the Prophet Mohammed.

It was referring to images published by Paris satirical magazine Charlie Hebdo, which saw 12 people killed at its offices by two Islamist brothers during three days of jihadist attacks in Paris that left 17 people dead.

Al-Murabitoun last month said it had pledged allegiance to the Islamic State group -- but Belmokhtar distanced himself from the declaration and vowed continued backing for Al-Qaeda in what was interpreted as evidence of a serious schism.

Libya's internationally recognised government said on Monday Belmokhtar had died in the US attack, the first air strike by Washington on the country since Moamer Kadhafi's regime fell in 2011.

The Pentagon said that while Belmokhtar had been the target, it was still awaiting confirmation of his death.

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