British police arrested three passengers aboard a Dubai-bound Emirates airliner at London's Heathrow airport on suspicion of making a bomb threat, police said.

Sky News television quoted police sources as saying initial searches had found no actual threat to the flight, indicating that the incident may have been an ill-judged prank.

The men, aged 58, 48 and 36, were taken into custody for making verbal threats against the crew before take off, the police said in a statement. 'They have been arrested on suspicion of making a bomb threat,' they added.

An airport spokesman said other flights at Britain's biggest airport were unaffected. Witnesses told Sky that armed police with sniffer dogs boarded flight EK004, which had been due to take off at 2000 GMT, and swiftly arrested the men.

'A verbal threat was made to staff. Police were alerted and armed officers boarded the plane,' the police statement said.

'Police are searching the aircraft and all passengers have been removed from the plane.'     Airports around the world have been on high alert since a failed bombing attempt on a Detroit-bound plane last month.

Britain announced tighter security measures this week, with plans to use full body scanners at Heathrow within three weeks.

'There was no shouting or screaming ... They took them away quickly and brought on some dogs to have a sniff around,' Cameron McLean, a passenger on the grounded Boeing 777, told Sky. – Reuters