Irregularities found in pilot licences at Pakistan International Airlines (PIA) represent a "serious lapse" in safety controls, global airlines body IATA said after the carrier grounded one third of its pilots.
"We are following reports from Pakistan regarding fake pilot licences, which are concerning and represent a serious lapse in the licensing and safety oversight by the aviation regulator," an IATA spokesman said, adding that the organisation was seeking more information.
Pakistan's civil aviation authority has found that some 150 of PIA's 434 pilots have "dubious licences", the airline said.
The decision comes as an inquiry into a PIA crash last month, in which 97 people were killed, points to pilots not following procedures, while a government minister said the cockpit voice recorder suggested the pilots were distracted by a conversation about the coronavirus.
All of the pilots under investigation would be grounded, a spokesman for the airline said.
The PIA has a fleet of 31 aircraft that fly domestic and international routes.
Successive governments have tried to overhaul loss-making PIA over the years but with little sign of success.
The airline's latest accident came late last month when an Airbus A320 on a domestic flight came down short of the runway in the southern city of Karachi, killing all but two of those on board.
The aviation minister told parliament this week the plane's pilots and air traffic control officers had not followed procedures and the two pilots had been pre-occupied by a discussion of the coronavirus shortly before the crash.
The investigation into pilots' qualifications came after a 2018 crash when it was found that the test date on the license of the pilot involved had been a holiday - suggesting it was fake as testing could not have taken place on that day.
Another pilot had been out of the country on the date stamped on his flying certificate.