Al Qaeda-linked Somali Islamist group Al Shabab said it has killed French intelligence agent Denis Allex in retaliation for a failed French operation to free him, BBC reported Thursday.
The French government said it believes Allex was killed during last week's raid, in which two French commandos also died.
Allex was kidnapped in Somalia in July 2009.
Al Shabab said on its Twitter account that Allex was killed Wednesday.
It had earlier said that because of the rescue attempt, France would be responsible for his death.
The group also cited France's intervention against Islamists in Mali in its decision to kill Allex, BBC said.
Last week, about 50 French commandos launched an assault by helicopter on the Al Shabab stronghold of Bulo Marer, believing Allex was being held in the town.
Al Shabab said it had advance warning of the attack and Allex was not in Bulo Marer at the time.
France said 17 militants were killed during the fighting.
Several civilians were also reported to have been killed.
Al Shabab later said it has taken the decision to execute their hostage to avenge the civilians killed during the French operation.