Munich - More than 20 fairgoers had to be evacuated from a roller-coaster that got stuck 30 metres above ground at Munich's Oktoberfest beer festival on Saturday.

Most were able to leave the "Olympia Looping" via an emergency stairway but four young people had to be lifted to safety with the help of an aerial platform, a spokesman for the city's fire brigade said.

No one was injured in the incident. Preliminary investigations showed a problem with a diesel motor caused the roller-coaster to grind to a halt at the highest point of the ride.

It was not immediately clear when the popular attraction would be back in service. dpa