Russia's space agency has reported a glitch at the International Space Station that caused its position in orbit to change.

Roscosmos said the engines of a Soyuz spacecraft that is docked at the station unexpectedly started on Tuesday during testing of the radio system that controls the docking procedure.

The agency said steps were taken to stabilize the station and the crew was not in danger, adding that specialists were working to determine what caused the engines to start.

Two Soyuz spacecraft are docked at the station, and one of them is scheduled to return three of the six crew members to Earth on Thursday.

Roscosmos did not specify which capsule had the malfunction, but said the landing would go ahead as planned.