Amenas natural gas field in the eastern central region of Algeria, where Islamist militants raided and took hostages.
Islamic militants have told a Mauritanian news outlet that that 35 hostages were killed but seven are still alive after Algerian military helicopters strafed a gas complex deep in the Sahara.
The spokesman for the Masked Brigade, which claimed responsibility for the attack Wednesday on the Algerian gas plant, said Thursday the survivors included three Belgians, two Americans, a Briton and a Japanese citizen.
The information came from the Nouakchott Information Agency, which often carries reports from al-Qaida-linked extremist groups.
The militant spokesman said the kidnappers were attacked by Algerian helicopters as they tried to leave the complex.
Algeria's news agency, citing local police, said four foreign hostages were freed in the operation.
The Algerian government would not immediately comment and the Associated Press could not confirm the information independently.