Computers controlling the orbit of the International Space Station, as well as its supplies of oxygen and water, have failed.

Experts in orbit and on the ground are trying to fix the computers, which have never failed in this way before.

The Space Shuttle Atlantis, which is currently docked to the station, has extended its mission for another day to try and resolve the problem.

"Russian flight controllers will be working overnight to resolve a problem with the Russian segment computers that provide back-up attitude control and orbital altitude adjustments," said Nasa in a statement.

"For now, the station's control moment gyroscopes are handling attitude control, and the Shuttle's propulsion is providing back-up."

The computers control the booster rockets that maintain the Space Station's orbit and enable it to dodge orbiting space debris. They also control the water and oxygen recycling systems without which the station has air for only another 56 days.

If at least one of the computers cannot be fixed by the time the Shuttle is due to depart, station commander Fyodor Yurchikhin, flight engineer Oleg Kotov and Nasa astronaut Clayton Anderson will have to hitch a ride back to Earth with Atlantis.

The Shuttle's mission has already been extended two days beyond its planned duration because of damage to the thermal insulation that occurred during takeoff.

The astronauts will attempt to fix the problem with staples or by sewing the hole up using steel thread.