The staffs have been on picket lines since Tuesday, resulting in the cancellation of around 250 flights, the stranding of 45,000 passengers and causing losses of around $19 million for the airline, which is on the brink of bankruptcy.

Employees are furious at management plans to farm out lucrative European and US routes to Turkish Airlines in order to avert bankruptcy. They want the plan scrapped and the managing director sacked.

Two rounds of crisis talks between union leaders and government representatives have ended without any breakthrough.

PIA says at least 250 flights have been cancelled since the strike began on Tuesday, including to Britain, the Middle East, Europe and Asia.

"Like yesterday, we have total shutdown today. We had to cancel about 120 flights on Thursday and as many today," PIA spokesman Mashhood Tajwar told AFP.

Of the 250 cancelled flights, 200 were domestic and 50 international.

The airline provides the only direct service from Pakistan to Britain, Europe and North America.