Japan's prime minister says seven Japanese citizens have been confirmed dead in a hostage crisis at an Algerian oil field.

Prime Minister Shinzo Abe said Monday that three other Japanese remain missing and unaccounted for.

Abe told a government crisis taskforce that he was informed of the deaths by Japanese officials in Algeria.

The victims worked for a Japanese engineering company, JGC Corp.

Militants seized an Algerian gas field and held foreign workers hostage for four days until Algerian special forces stormed the plant on Saturday.

Algerian Prime Minister Abdelmalek Sellal said Monday that 37 foreign hostages were killed.