Two British men have been arrested after fighter jets were launched to divert a civilian plane carrying nearly 300 passengers from Pakistan to England after a threat call was made to air traffic control.

Britain's Ministry of Defence said on Friday that the Typhoons were launched from RAF Coningsby, in Lincolnshire, to investigate an incident involving a civilian aircraft.

The civilian plane was diverted from Manchester Airport to Stansted Airport, which is used to handle security incidents on planes, after the men allegedly threatened to destroy the plane.

British security forces and police said that early indications suggest the plane had not be subject to a terror attack.

Al Jazeera's Rory Challands, reporting from London, said the men, aged 30 and 41, had been arrested on suspicion of endangering an aircraft.

"The plane is safely on the ground and has been isolated in a part of the airport away from passenger planes," our correspondent said.

"It does seem that the initial fears surrounding this incident are starting to calm down a bit."

Our correspondent said that concerns were raised about the flight about ten minutes before it was due to land after a threat call was made to the UK's air traffic control.

Pakistan International Airlines confirmed that Flight P709, travelling from Lahore to Manchester, was involved.

Spokesman Mashood Tajwar said the airline had been unable to contact the pilot of the Flight P709 despite repeated attempts. He said 297 passengers and 11 crew members were on the diverted plane.

The MOD said the incident was now a police matter and that the ministry's involvement was over.

"Typhoon aircraft from RAF Coningsby have been launched to investigate an incident involving an aircraft in UK airspace," the MoD spokesman said, adding that Typhoon planes can be scrambled if the pilot or crew of a passenger aircraft sends out a passenger signal.

"The purpose of going up is to investigate what the situation is. Often when a Quick Reaction Alert aircraft is launched the details are not known, but it is known that a signal has been sent."

"Part of the purpose of sending a Typhoon up is to have a look and see what they can see."

Essex Police confirmed that "an incident has occurred" on the plane and that police and partners are responding.

"Essex Police have boarded a passenger plane diverted to Stansted Airport and two men have been arrested on suspicion of endangerment of an aircraft," the force said in a statement.

"They have been removed from the plane."

The plane will remain at its current location and will be subject to forensic examination by specialist officers.

Al Jazeera's Simon McgGegor Wood, reporting from Stansted, said the passengers had been disembarked and would be sent to Manchester later today.