British, Spanish and Norwegian oil companies are evacuating workers from Algerian energy facilities following the hostage-taking by Islamic militants in the Sahara desert and Algeria's attempt to free them.
BP said plans were under way to bring some non-essential workers out of the country.
Spain's Compania Espanola de Petroleos said it moved workers from two Algerian facilities to the centre of the country as a precautionary measure and its Algeria operations were functioning normally. Spain gets nearly half its natural gas from Algeria.
The hostages were taken by militants linked to Mali's rebel Islamists at a remote Sahara natural gas plant on Wednesday. The site is operated by BP, Statoil and the Algerian state oil company Sonatrach.
A Japanese company, JGC, provides services for the facility.