A glitch at the International Space Station on Tuesday caused its position in orbit to change, but the crew was not in danger, the Russian space agency said.

Roscosmos said the engines of a Soyuz spacecraft docked at the station unexpectedly started during testing of the radio system that controls the docking procedure. Steps were taken to stabilize the station and specialists were now working to determine what caused the engines to start, the agency said.

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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.

Tuesday's problem follows the failure of a Soyuz booster rocket that was supposed to send a robotic Progress cargo craft to the space station in April. That failure led to a delay in the crew landing and the launch of three new crew members.