"The Progress craft is already at Baikonur (cosmodrome in Kazakhstan) and preparations for the launch are on course," said Rosaviakosmos spokesman Vyacheslav Mikhailichenko.

The vessel will carry supplies of water, food and oxygen for the crew as well as fuel for the station, he added.

Russian flight commander Yury Malenchenko and US flight engineer Edward Lu arrived at the space station in late April for a six-month mission.

Russia has been the only country servicing the 16-nation orbiting space station since the United States grounded its shuttle programme following the Columbia disaster on February 1.

SPACE.WIRE