An overnight sit-in on board a Lufthansa plane by 56 Iranian monarchist protesters ended peacefully at Brussels airport yesterday after Belgian police escorted them all off the aircraft.

The unarmed group of men, women and three children refused to leave the Boeing 737 flight from Frankfurt for 16 hours in a protest against Iran's Islamic government.

"The plane is empty now .. there was no violence at all," said police spokesman Olivier Vincent.

He said the protesters faced only "administrative arrest", which meant they would shortly be free to leave. One person was forcibly escorted off the plane at the end of the protest and another was treated by doctors after collapsing upon disembarking. Several riot control vehicles had assembled near the aircraft, which was flanked by police vans.

"We want the European Union to remove the Islamic leaders from Iran," Armin Atshgar, one of the protesters, told Reuters by mobile phone during the sit-in. "We want to remove the mullahs from power."