From the BBC:
Two men have been arrested after RAF Typhoon jets were launched to investigate an incident involving a civilian aircraft within UK airspace earlier this afternoon.
A Pakistan International Airlines plane had been diverted from Manchester to Stansted Airport in Essex (30 miles north east of central London).
Two men are being held on suspicion of endangerment of an aircraft, Essex Police said.
RAF Typhoons
They said the men had been removed from the plane.
The plane, flight number PK709, reportedly left Lahore at 09:35 local time. It was due in at Manchester at 14:00 BST.
'Signal sent'
A Manchester Airport spokesman said: "A Pakistan International Airlines aircraft which was due to land at Manchester Airport at 13.30 BST today has been diverted to our sister airport London Stansted, where the authorities are investigating."
The MoD said responsibility for the incident had passed to Essex Police and the Home Office.
An MoD spokesman said the incident was now a police matter and that "our involvement is over".
He said Typhoon jets could be scrambled after the pilot or crew of a passenger aircraft sends out an emergency signal.
"The purpose of going up is to investigate what the situation is," he said.
"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."
A Pakistan International Airlines (PIA) spokesman Zufiqar Bijarani told CNN: "We have been told there may have been a bomb threat." But he did not say if he had anything to confirm or deny this.
Stansted Airport said on Twitter that it was operating normally.
PIA said there were 308 passengers on board, as well as 14 crew including pilots, with a mixture of Pakistani and British passport holders.
BBC News - Two held after RAF Typhoon jets escort Pakistan plane over UK
