Customs officials said that they got a tip-off that narcotics would be smuggled on the PIA aircraft flight PKI-221 from Lahore to Dubai.
The flight was instructed to land at Karachi airport and a search of the aircraft was carried out and it was discovered there was 3.1 kilogrammes of heroin was hidden in one of the bathroom, an official said.
He said sniffer dogs were used to comb the aircraft and the narcotics were hidden behind the panel sheets in the bathroom.
An investigation into the incident has been initiated. In the past, PIA stewards have been arrested and sacked for trying to smuggle brand new Iphone models into Karachi while returning on international flights from the US or UK.
PIA crew members have also been arrested in the past for attempting to smuggle narcotics on flights bound for international destinations.
