Japanese, Malaysian and Filipino nationals are believed to be among hostages being held by Islamist militants at a gas field in southern Algeria, according to a recorded phone conversation with a hostage aired by a French news channel on Wednesday.

France 24 broadcast a short excerpt of the conversation with one of the hostages, believed to be French, wherein he said he was being held along with English, Japanese, Filipino and Malaysian nationals in a booby-trapped building at the In Amenas gas field. He also told the station that individual hostages had belts of explosives attached to them.

It was not immediately clear if the hostage was speaking under constraint from his captors.

There were mixed reports on the number of people who were taken hostage at the oil facility jointly operated by British oil giant BP, Norway’s Statoil and state-run Algerian energy firm Sonatrach.

Militants told Mauritian media they were holding 41 Westerners, including French, British and Japanese citizens, as well as seven Americans.

Japanese engineering company JGC Corp. said five Japanese workers were among the hostages, reports The Japan Times. Reuters reported that a French citizen is among the captives, though France has yet to confirm the report.

The militants claimed they were Al Qaeda loyalists from northern Mali and said the attack was in retaliation for the French military intervention against armed Islamists who seized control of northern Mali in April last year, AFP reports.

Algerian forces are currently negotiating with the militants for the release of the hostages, an Algerian security official said on condition of anonymity.