(CNN) -- France confirmed for the first time Saturday that Islamist militant Abdelhamid Abou Zeid was killed amid fighting by French forces in northern Mali late last month.
Abou Zeid's death in the Ifoghas Mountains had been widely reported but the French government declined to confirm it pending the results of DNA testing.
The death of one of the major figures in al Qaeda in the Islamic Maghreb "marks an important stage in the struggle against terrorism in the Sahel," said a statement from the office of French President Francois Hollande.
Abou Zeid was considered one of the group's most ruthless commanders, having seized at least a dozen foreigners for ransom.
The French president's office said there was no new information regarding a second man reported to have been killed in the fighting in northern Mali, jihadist commander, Moktar Belmoktar. DNA testing was also being conducted to confirm his death.
Belmoktar is believed to be behind a large scale attack at an Algerian gas plant in January that left dozens of hostages and militants dead.
At the beginning of this year, Abou Zeid joined other Islamist forces making a push southward toward the capital, Bamako.
But when the Islamist advances prompted a French intervention, he moved to the area around the less accessible city of Kidal, close to the virtually impenetrable Ifoghas Mountains.
French and allied forces, including Malian and Chadian troops, have made significant inroads in recent weeks combating Islamist extremist fighters in Mali.
But fighting continues in the remote northeastern part of the West African nation.
Nearly 50 aerial sorties were flown in the past few days, most of them in the Ifoghas Mountains region and along the Niger river between Gao and Timbuktu, the French Defense Ministry said Thursday.
French ground forces, supported by troops from Chad, have been hunting armed terrorist groups in amongst the valleys of the massif, the ministry said.
French involvement in the conflict began on January 11, the day after militants said they had seized the city of Konna, east of Diabaly in central Mali, and were poised to advance south toward Bamako, the capital.
In total, 4,000 French soldiers are deployed in Mali, according to the French Defense Ministry website, alongside 6,300 troops from Chad and the African-led International Support Mission to Mali.
Islamist extremists carved out a large haven in northern Mali last year, taking advantage of a chaotic situation after a military coup by the separatist party MNLA.
CNN's Per Nyberg, Tim Lister and Paul Cruickshank contributed to this report