A Pakistan International Airlines flight to Heathrow Airport has been intercepted by the RAF after reports of a disruptive passenger onboard.
An RAF spokesman said Quick Reaction Alert Typhoon aircraft from RAF Coningsby in Lincolnshire escorted the aircraft to Stansted Airport in Essex.
Essex Police said the diversion happened at around 3pm on Tuesday and the plane is on the ground at Stansted.
A force spokesman said officers are investigating the incident, which is "not believed to be a hijack situation or terror matter".
A spokesman for Stansted said the diverted plane was a Pakistan International Airlines flight from Lahore.
He added: "The aircraft is likely to continue its journey onwards to Heathrow today pending inquiries that the police are making into the individual on the aircraft."
An RAF Typhoon jet was scrambled in May 2013 in response to reports of disruption on board a Pakistan International Airlines flight from Pakistan to Manchester.
The Boeing 777 was escorted to Stansted.
Two men were arrested and went on trial accused of threatening to blow up the plane, but were cleared when the judge ruled they had no case to answer.
Typhoon pilots are on standby 24 hours a day to defend UK airspace.
Squadrons are based at RAF Coningsby, covering the south of the country, and RAF Lossiemouth in Moray, to cover the north.
The Quick Reaction Alert crews can take off within minutes to intercept aircraft which have caused concern.
This can be because they are Russian military aircraft, or civilian planes which have stopped communicating with air traffic control, are not following their flight plan or have sent an emergency signal.
On some occasions pilots are given permission to fly at supersonic speeds, which may result in a sonic boom, to reach the aircraft as soon as possible.
Ministry of Defence figures show that QRA were launched on 12 days in 2015, eight in response to Russian aircraft and four to investigate other planes.
Stansted is a designated airport for dealing with hijacks and major security alerts.
Such incidents are dealt with in a remote part of the airfield to the north-west of the terminal building.