However shortly before the landing communication with the Soyuz TMA-1 vessel was disrupted, and helicopters have been unable to locate the spacecraft and its team, mission control officials said.

Bowersox, Pettit and Budarin have been on the ISS since December. They were originally to have left in March, but their return to Earth was delayed because of the Columbia space shuttle disaster.

Columbia disintegrated during re-entry to the Earth's atmosphere on February 1, killing all seven crew members and leading NASA to suspend all shuttle missions, including those to the ISS.

Russian flight commander Yury Malenchenko and US flight engineer Edward Lu, who travelled aboard Soyuz to the space station are due to stay aboard the ISS for six months.

Russian spacecraft currently provide the only transportation to the space station.

SPACE.WIRE