Al Qaeda made the announcement via an audio recording passed on to the al-Jazeera broadcaster Thursday.
The recording confirmed that the men died as French troops closed in on the kidnappers, but left open the question of whether the men were executed by their abductors.
Questions of the cause of death of the two men, both aged 25, have roiled through France since the weekend's incident, especially after an autopsy showed that one man died of burns, while the other died of a bullet wound to the head.