ALGIERS, Algeria — Islamist militants have told a Mauritanian news outlet that Algerian military helicopters strafed the gas complex where they are holding hostages, killing 35 of the foreigners and 15 of the kidnappers.

The spokesman for the Masked Brigade, which had earlier claimed responsibility for the assault Wednesday on the gas complex deep in the Sahara desert, said Thursday that Abou El Baraa, the leader of the kidnappers, was also killed in the helicopter attack.

The information came from the Nouakchott Information Agency, which has often carried reports from al-Qaida-linked extremist groups.