BERLIN (AFP) - Lufthansa crew and passengers overpowered a man who tampered with a cabin door on a Frankfurt-to-Belgrade flight on Sunday (Dec 6), the German carrier said, insisting the safety of the plane had not been threatened.

"A passenger got up and tried to do something with the door, but was stopped by crew members and other passengers," said airline spokesman Andreas Bartels.

"The passenger was then restrained for the remainder of the flight in his seat and handed over to the authorities in Belgrade," he said.

"It was a normal door, which of course cannot be opened in-flight... it was not the cockpit door," he said, denying an earlier report on Serbian television. "The safety of the flight was not jeopardised and the flight landed safely in Belgrade".

Mr Bartels declined to provide details of the passenger's identity or nationality, or what the man said during the incident.

Serbia's state-run RTS TV reported that police had arrested a Jordanian man after he tried to force his way into the cockpit of the Lufthansa flight.

It said the man suddenly got up during the flight, banged on the cockpit door and demanded to be allowed to enter, threatening to open one of the Airbus A319's external doors while it was flying over Austria.

The man, who the Serbian press said had a US passport, had shouted that he wished to join Allah along with all the passengers, RTS said.

Flight crew and members of a Serbian handball team overpowered him and kept him subdued until the flight landed in Belgrade where he was arrested, the report said.

The head of the handball team's club, Milan Djukic, who was on the flight, said the man had seemed "nervous" before boarding the plane.

"I exchanged a few words with him and he was very nervous. Before take-off, the flight attendants made him change seats three times," Mr Djukic told private Serbian TV station Moja Prva.

"When he got up, he crossed through business class and started banging on a door demanding for that of the cockpit to be opened," Djukic said. "A crew member and one of our coaches calmed him down and persuaded him to sit back down."

For the rest of the flight, "these two men and two of our players kept him company so that he would stay calm," he added.

He said that after the plane landed, Serbian police boarded and arrested the man, who he said would be held for 48 hours for "provoking general danger".