The north African branch of Al-Qaeda said it will execute a French hostage unless four of its militants are freed from jail in Mali in 20 days, two US monitoring groups said on Monday.
Al-Qaeda in the Islamic Maghreb (AQIM) claimed last month it was holding Frenchman Pierre Camatte, who was seized in Mali in late November, as well as three Spaniards kidnapped in neighbouring Mauritania four days later.
US groups SITE Intelligence Group and Intelcenter, which monitor Islamist websites, said Al-Qaeda issued its ultimatum in a statement dated January 10.
"The mujahedeen have decided to inform the French and Malian governments of their only demand to release the French hostage Pierre Camatte -- the release of our four prisoners apprehended by the state of 'Mali' many months ago," Intelcenter said in a statement.
"Let France and Mali be forewarned, that we give 20 days to fulfill our just demand, or the two governments shall be fully responsible for the life of the French hostage," it said.
Camatte was snatched from a hotel in Menaka in the Sahel region of northern Mali, more than 1,500 kilometres (1,000 miles) from the capital Bamako, during the night of November 25.
Malian and Western security forces say the Frenchman, a regular visitor to Mali where he cultivates a plant known for its anti-malaria properties, is being held by a hardline faction within Al-Qaeda's north African branch.
AQIM claimed responsibility for killing a British hostage earlier this year, according to a Mali security source.