The crew made its way back from Heathrow Airport, where their passports were seized by British authorities who searched the plane and questioned them after landing from Islamabad on Monday.
According to Dawn, an inquiry has been launched into the issue.
British authorities confirmed on Wednesday that Border Force officers had found a "quantity of heroin" on board the PIA flight.
PIA spokesperson Mashhood Tajwar said British authorities had "thoroughly searched" and detained the flight crew after they landed at Heathrow.
The Pakistan carrier has come under fire for poor performance, low safety standards and the staff's unprofessional attitude.
Members of PIA crew have been sacked for smuggling contraband and assisting money laundering operations.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)