Units from Istanbul Police Department raided a heroin workshop Wednesday, which was disguised as a poultry farm in Turkey's northwestern province of Sakarya, confiscating approximately one ton of heroin.

In the operation directed by Istanbul Police Chief Mustafa Çalışkan, police units first blocked the road leading to the farm and then raided the facility.

In addition to one ton of packaged heroin ready to be delivered, the police also seized the chemical substances used in its production. The seized amount is the largest in 15 years, apart from sea shipments, police sources said.

The police stated that tunnels were found connecting different buildings of the facility.

Five people were taken into custody after the raid.