Algerian forces are scouring the Sahara for the five foreigners missing since the gas plant massacre.
"Are they dead? Did they attempt to flee the site after the attack like some other expatriates? Are they lost in the desert after taking a wrong turn?" said a spokesman for prime minister Abdemalek Sellal. "These are all questions we ask ourselves."
The desert in the area is flat rocky and featureless and while roasting hot in the summer, during the winter months the temperature drops to 3C at night, with average highs of 18C during the day.
An al Qaida-linked band of fighters attacked the vast natural gas complex on January 16, killing 37 hostages.
BP said that the operations at the plant are still suspended.