The death toll from the terrorist siege at a natural gas plant in the Sahara climbed to at least 81 on Sunday as Algerian forces searching the refinery for explosives found dozens more bodies, many so badly disfigured it was unclear whether they were hostages or militants, a security official said.

Algerian special forces stormed the plant on Saturday to end the four-day siege, moving in to thwart what government officials said was a plot by the Islamist militants to blow up the complex and kill all their hostages with mines sown throughout the site.

The government said after the assault that at least 32 extremists and 23 hostages were killed. Then, on Sunday, Algerian bomb squads sent in to blow up or defuse the explosives found 25 bodies, said the security official, who spoke on condition of anonymity because of the sensitivity of the situation.