The man was observed by customs officials who noticed that while in the baggage claim area, he was looking around nervously, was constantly on the phone, and selected the green channel - for those with nothing to declare.
Officers requested an inspection of the bag, and noticed that it was mostly empty, yet was heavy. A scan of the bag revealed a false bottom, which when drilled into, revealed the suspected narcotics.
The presence of heroin was confirmed by a field-test kit. Police were called, and the man was then placed under arrest.
An accomplice, also from Pakistan and living in Madrid, was discovered staying at a hotel in Vienna, and was arrested for further questioning.
Both men are likely to face charges for the illegal importation of controlled drugs.
The arrest and seizure occurred in early May, but were kept confidential in order not to hamper the on-going investigation.