Deaths of al-Qaida leaders increase fear of retaliation in Mali The reported deaths in northern Mali of two top commanders of al-Qaida's North African wing has heightened fears for the safety of French hostages. BAMAKO, Mali, March 4 (UPI) -- The reported deaths in northern Mali of two top commanders of al-Qaida's North African wing has heightened fears for the safety of four French hostages held by Islamist forces in the West African desert. Chadian troops claimed Saturday they had killed Mokhtar Belmokhtar, a key leader of al-Qaida in the Islamic Maghreb and a veteran of the Afghanistan war against the Soviets in 1979-89, in heavy fighting around the Ifoghas Mountains in northern Mali. Chadian President Idriss Deby said Friday his forces had also killed Abdel Hamid Abou Zeid, another important AQIM leader, in fighting in the same region. Jihadist forces withdrew into the mountains of northern Mali after being pushed out of southern Mali by French troops who intervened in France's former colony Jan. 11 to crush heavily armed jihadists who established a stronghold there in April 2012. There has been no confirmation by the AQIM and its Malian Islamist allies, nor by independent sources, that these two key figures have been slain. France, with forces and intelligence assets on the ground, has made no comment on the claims by the troops from Chad, another former French colony which has been supporting the French task force in Mali. This could be because Paris fears for the lives of the four French captives -- Pierre Legrand, Thierry Dol, Daniel Larribe and Marc Feret -- who were kidnapped in September 2010 in Niger where France has major uranium mining interests. Algeria, which has been fighting Belmokhtar and Abou Zeid for two decades, also hasn't been able to confirm the deaths. However, French and Algerian media reported that relatives of Abou Zeid have provided French authorities with DNA samples that could verify his identity. If these two key AQIM figures have been killed it could be a major blow to the jihadist groups fighting in northern Mali and which regional and European powers view as a transnational threat. It also suggests that the 4,000-person French task force, supported by airstrikes and Chadian desert fighters trained in counterinsurgency operations by the U.S. Army, are making substantial progress battling through the rugged 8,500-square-mile mountain chain where the jihadists are holed up after nearly two months of combat. Meantime, the death of another veteran jihadist commander, a 20-year Sudanese guerrilla veteran known as Abu Hazim al Sudani, was announced on internet forums used regularly by al-Qaida. Like hundreds of foreign jihadists who flocked to join AQIM after the Islamists seized northern Mali in early 2012, al-Sudani traveled with 150 of his countrymen to aid AQIM after France's Operation Serval was launched in January. He was reportedly killed in a French airstrike but the date and location of his death weren't announced. Abou Zeid, AQIM's most feared commander who largely operated in the Sahara desert in southern Algeria, as well as Mali, Chad, Niger, Senegal and Burkina Faso, specialized in kidnapping Europeans over the last five years. He amassed ransoms worth around $80 million that filled AQIM's warchests. The group has been part of al-Qaida since 2009. The onetime smuggler turned jihadist, who married the daughters of Tuareg tribal chiefs to consolidate his power in the Sahara and the Sahel region, is believed to have executed at least two European hostages. They were Edwin Dyer of Britain in 2009 and Frenchman Michel Germaneau in 2010, when French Special Forces tried to rescue him. The fear is that if he is dead, his followers may kill the four Frenchmen they now hold. So far as is known, that hasn't happened. Belmokhtar, equally ruthless, supposedly broke with AQIM a few months ago to form a splinter group. But he masterminded the seizure of the In Amenas natural gas complex in Algeria's southeastern desert near the Libyan border Jan. 16, five days after the French attacked in Mali. The four-day siege ended when Algerian Special Forces stormed the complex, killing 48 foreign captives and 32 of the estimated 40 attackers. Belmokhtar, another former smuggler and veteran of the Algerian civil war during the 1990s, has been reported killed several times in recent years. But he has always reappeared. French intelligence calls the elusive Algerian "the uncatchable."