BACTERIA discovered on the surface of the International Space Station may not be from Earth, a Russian cosmonaut claims.

Anton Shkaplerov, an ISS expedition flight engineer who will take his third trip to the space station in December, said that living bacteria harvested from the metal skin may be extraterrestrial.

Microorganisms from Earth have been found on the station's skin before but they have got there thanks to the ionosphere lift phenomenon, where substances from Earth rise into the atmosphere.

Shkaplerov said: "Bacteria that had not been there during the launch of the ISS module were found on the swabs.

"So they have flew from somewhere in space and settled on the outside hull."

He added that the samples are being probed by scientists and seem to be safe.