LONDON — Algerian forces launched a final assault Saturday against Islamist militants holding foreign hostages at a desert energy complex, resulting in the deaths of 11 kidnappers and their seven remaining captives, according to Algerian and French news reports.

Reports of the raid — which unfolded despite calls for restraint from foreign governments, including the United States, whose nationals were being held captive — remained sketchy and unverified, but state media said the operation targeted a remaining stronghold of militants at the sprawling, remote facility run by BP, Norway’s Statoil and Algeria’s state-run energy company. Reports from Algeria’s state news agency and France’s AFP, both quoting an unnamed Algerian security official, suggested the militants may have killed their hostages as forces approached.