The officers boarded the Dubai-bound Emirates EK004 flight, which had 331 people inside, after air crew alerted police, Sky News reported.

Police entered the plane when it was about to take off at 8 pm local time last night (0130 HRS IST Saturday). The flight was grounded for over three hours.

Emirates said the incident occurred after "remarks" were made as the plane prepared for take-off.

Three men, aged 58, 48 and 36, have been arrested on suspicion of making a bomb threat, the report quoted the Metropolitan Police as saying.

The three men were handcuffed and dragged off the flight by officers wearing full body armour. One allegedly made a 'verbal threat' as the plane taxied towards the Terminal 3 runway, Mail Online reported.

Witnesses described the main suspect as a white man.Passengers remained on board while officers emptied overhead lockers and sniffer dogs were brought on to the Boeing 777 to search for potential explosives.

Up to eight police vehicles surrounded the plane, although no ambulances were present.
The incident comes amid heightened security at airports across the world in the wake of the botched Christmas Day bombing of a US plane by 23-year-old Nigerian Umar Farouq Abdulmutallab.

Heathrow Airport remained open, despite the security alert.Officers are not believed to have found any suspicious substances on the Emirates aircraft.

"Police just swarmed the guy (one of the three men) and rushed him out. I think he was a white male. There was another one but I didn't see him," passenger Cameron McLean told Sky News.

A Scotland Yard source was quoted as saying by Mail Online that "we are aware of a security incident at Heathrow. The airport and terminal remains open. We have not found anything."

A spokesman for Heathrow Airport also confirmed the incident on the EK004 flight to Dubai.

"Police are attending. It's not affecting the rest of the airport which remains opens," he said.

The incident came shortly after Abdulmutallab, a former student of University College London, was arraigned before a Michigan court in the US, where he pleaded not guilty to charges of attempting to blow up the Detroit-bound airliner from Amsterdam.
Abdulmutallab was indicted on six-count for his attempt to blow up the North West Airlines plane, carrying 300 people on board, on December 25.