An Algerian air strike killed 34 hostages and 15 of their extremist kidnappers at a desert gas field on Thursday.

An Algerian air strike killed 34 hostages and 15 of their extremist kidnappers at a desert gas field on Thursday, the ANI news agency quoted a spokesman for the kidnappers as saying.

"Thirty-four hostages and 15 kidnappers were killed in an (air) raid by the Algerian army," the spokesman said in remarks that have not been independently confirmed.

Amongst the killed was Abu al-Baraa, who led the Wednesday operation in which 41 foreigners and scores of Algerians were seized.

The spokesman said Algerian aircraft attacked the kidnappers when they tried to "transport some of the hostages in vehicles to a location to the south."

The Algerian army was able to free four hostages later on Thursday, including two Britons, a Frenchman and a Kenyan, being held by extremist gunmen at a remote gas plant in southeast Algeria, the APS news agency reported.