ISLAMABAD: Pakistan International Airlines (PIA) said Thursday that it was investigating emailed threats that said two of its planes had bombs on board, forcing one of them to divert abruptly to Istanbul.

PIA said it received two emails late Wednesday claiming there were bombs on the two flights and directed the pilots to land immediately at the nearest airports. No bombs were found on either plane.

“The safety department of the airline is conducting the investigation into the emails...but there is no outcome so far,” PIA's director of flight operations, Naveed Aziz, told AFP.

“They are also coordinating with the Airport Security Force (ASF) and other agencies responsible for safety, but are yet to reach any conclusion.”

A senior PIA official who requested anonymity said computer experts at the airline and security forces were carrying out the inquiry.

“This is a serious matter and if not nipped in the bud such hoax emails in future could damage our reputation and bring a bad name for our country internationally,” the official told AFP.

The first plane had departed Lahore, bound for the British city of Manchester, when it was diverted to Istanbul's Ataturk Airport, causing panic among the 378 passengers, airport authorities and Turkish media reported.

The passengers were evacuated from the aircraft and sniffer dogs searched the Boeing 777-300 EA for three hours before the bomb threat was declared a hoax.

A second flight from Lahore landed safely at its planned destination in Kuala Lumpur after a threat was received while it was mid-air.

A search of that aircraft found no explosive devices on board.

“We cannot ignore such threats, we are looking into the matter,” said a spokesman for the civil aviation authority, Pervez George.

An airport security official said safety restrictions had been tightened at Pakistani airports following the hoax.