The orbiting International Space Station has shifted in position after an engine glitch on a docked spacecraft which is due to bring astronauts back to Earth this week, Russia said.

The engines of the Soyuz spacecraft "switched on unscheduled which led to an insignificant change in the position of the ISS", Russia's space agency, Roscosmos, said in a statement on its website.

The Soyuz is docked at the ISS in readiness to take three astronauts home on Thursday, and Russia said "the necessary measures had been taken to stabilise" the space station and the glitch would not affect the astronauts' return.

"There is no threat to the crew of the ISS, the station itself or the return of the Soyuz TMA-15M ship to Earth on schedule," the space agency said.

The engines switched on for "less than a minute" during testing of the automatic docking system, a space industry source told the RIA Novosti state news agency.

Another source told the Interfax news agency that mission control probably gave the wrong command from Earth, meaning the Soyuz ship did not malfunction.

Russia's troubled space programme has experienced a series of recent failures. It was forced to delay the departure and landing of astronauts in May after a supply ship fell back to Earth after a rocket failure.

The space agency said the supply craft's design will be altered to prevent the problem occurring again with that particular type of rocket.

The next manned mission to the ISS is due to blast off between July 23 and 25, launching from Kazakhstan and carrying astronauts from Russia, Japan and the United States, Roscosmos said on Tuesday.