KARACHI, Pakistan (Reuters) - Pakistan has arrested at least 12 staff of its national carrier following the discovery of 6 kg (13.23 lb) of heroin in the toilet of an aircraft bound for Dubai, an airline spokesman said on Monday.

The latest instance of misbehavior by the staff of cash-strapped Pakistan International Airlines was uncovered after the military-run Anti-Narcotics Force raided a flight from Lahore to Dubai flight on Saturday, Danyal Gilani said.

"Around a dozen employees of PIA have been detained and are being interrogated in connection with heroin seizure," he told Reuters. "If proven guilty, they will face action with respect to their jobs, in addition to the legal consequences."

In June last year, the airline sacked five cabin crew who had been detained in Britain on accusations of trying to smuggle mobile phones and foreign currency.

In 2013, a PIA pilot was jailed for nine months in Britain after being found to be over three times Britain's legal alcohol limit for flying, just before he was due to take off with 156 people aboard.

For nearly three years, the government has struggled to find private buyers for the airline. Employees staged a three-day strike in February to oppose privatization.

(Reporting by Syed Raza Hassan; Writing by Mehreen Zahra-Malik; Editing by Clarence Fernandez)