DAKAR, Senegal -- Chad's military said Saturday that its soldiers in Mali had killed Mokhtar Belmokhtar, the mastermind of the January seizure of an Algerian gas plant that left at least 37 foreign hostages dead.
Mr. Belmokhtar's death was announced on state television in Chad, but has not been confirmed elsewhere.
"Today, Saturday, at noon, Chadian armed forces on mission in Mali totally destroyed the principal base of the terrorists and narcotraffickers in the Ifoghas mountain range," Chad's armed forces spokesman, Gen. Zakaria Ngobongue, said in a statement on national television. He said several terrorists, including "including the chief, Mokhtar Belmokhtar," had been killed in the operation.
Soldiers from Chad are fighting Islamist militants in Mali as part of an international force led by France that is seeking to oust the militants from northern Mali.
The French Defense Ministry spokesman, Col. Thierry Burkhard, said the ministry had no information on the claim by Chad and could not confirm it. American military and counterterrorism officials said only that they were aware of the reports and were seeking confirmation.
Other claims of the battlefield deaths of famous militants have proved false and positive identification can in some cases take days or weeks.
Chad said Friday that its forces had killed Abdelhamid Abu Zeid, the most important commander in Al Qaeda's regional franchise, in combat in Mali. The Algerian newspaper El Khabar reported that DNA samples from the body presumed to be that of Mr. Abu Zeid had been sent to Algeria, where he was born and where some of his relatives live, but neither French nor Algerian officials have confirmed his death.
The January raid in Algeria, which Mr. Belmokhtar claimed to have organized, was carried out in reprisal for the French intervention in Mali and for Algeria's support for the French war against Islamist militants in the region, Mr. Belmokhtar's spokesmen said at the time.
Mr. Belmokhtar, 40, was born in the Algerian desert city of Ghardaïa, 350 miles south of Algiers. Western officials consider him a notorious militant, who had been active in smuggling, kidnapping and fighting for decades in the Sahel, which includes Mali, Mauritania and Niger. But with the attack on the Algerian gas plant, he suddenly became one of the best-known figures associated with the Islamist militancy sweeping the region and agitating capitals around the world.
The attack led to a four-day hostage crisis that was ended by an Algerian military raid. At least 37 foreign hostages, including three Americans, were killed, along with about 30 militants.
In a recent diplomatic cable, the United States envoy in Algiers, Henry S. Ensher, urged the Obama administration to make the pursuit of Mr. Belmokhtar a priority, administration officials said. At a meeting of President Obama's top national security deputies at the White House last last month, there was broad agreement that Mr. Belmokhtar and members of Al Qaeda in the Islamic Maghreb should be aggressively pursued, according to a senior American official.
Mr. Belmokhtar was one of four leaders of Al Qaeda's North Africa branch, known as Al Qaeda in the Islamic Maghreb, during the 2000s. He fought against the Soviets in Afghanistan in the 1980s, and was known as "the One-Eyed" or "Marlboro Man," because of his extensive trafficking in contraband cigarettes.
In the 1990s he was a leading member of the Qaeda group's predecessor, the Salafist Organization for Preaching and Combat, in the jihadists' bloody fight against the Algerian government, and later became the architect of the group's affiliation with Al Qaeda, through contacts with Osama bin Laden, according to experts.
He broke with the group last year to form his own organization, the Signed-in-Blood Battalion, sometimes translated as the Signatories for Blood.
The leader of Al Qaeda in the Islamic Maghreb, Abdelmalek Droukdel, said that Mr. Belmokhtar had strayed from "the right path," according to a Malian official.
Dominique Thomas, a specialist in radical Islam, was quoted in the French newspaper Le Monde as saying that Mr. Belmokhtar's smuggling and trafficking activities ran counter to Al Qaeda's effort to present itself as a virtuous organization.
Mr. Belmokhtar allied his new group with the Movement for Oneness and Jihad in West Africa, another Islamist group that had broken off from Al Qaeda.
Martin Zoutane contributed reporting from Ndjamena, Chad; Steven Erlanger from Paris; and Eric Schmitt from San Francisco.
This article originally appeared in The New York Times.