"There was a family of eight to 10 people on the plane and they were quarrelling among each other," the PIA source said.
"When PIA staff approached them and asked them to calm down, they told them to go away otherwise they would blow up the plane.
"PIA staff became scared and they raised the alarm to avoid any untoward situation."
A spokesman for the Ministry of Defence said that Typhoon jets had been launched from a Royal Air Force base after the incident was signalled by the plane's crew, shortly before the plane was due to land in Manchester at 1230 GMT.
"Typhoon aircraft from RAF Coningsby have been launched to investigate an incident involving an aircraft in UK airspace," the MoD spokesman said.
After the plane landed, the MoD spokesman said the incident was now a police matter and "our involvement is over".
Typhoon planes can be scrambled if the pilot or crew of a passenger aircraft sends out a passenger signal, he added.
"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."
The incident came just hours after a British Airways plane was forced to make an emergency landing at Heathrow Airport with smoke billowing from one of its engines.
Heathrow was temporarily forced to close both its runways while emergency crews put out a fire on the Oslo-bound Airbus A319, causing heavy disruption at one of the world's busiest airports.
A British Airways spokesman said the incident was "a purely technical issue".
- additional reporting, AFP
- AAP
