Police have halted the popular "Rock am Ring" festival in western Germany over a "terrorist threat situation" and have asked attendees to clear the festival site so that an investigation can take place, event organizers said in a statement on Friday.

The rock festival in the western German town of Nuerburg is usually visited by tens of thousands of rock fans and takes place over a long holiday weekend.

"Because of a terrorist threat situation, the police have asked the organizers of 'Rock am Ring' to interrupt the festival temporarily as a precautionary measure, also so that they can carry out investigations in the event space," the statement said.

"All visitors are requested to leave the festival site in a controlled and quiet manner and make for the exits and camping sites."