Four police officers were taken to hospital for treatment after being exposed to chemicals while attending a motel at Taree.
About 1am Saturday police went to a motel room on Commerce Street after receiving calls about a domestic dispute.
While on scene, officers allegedly found a clandestine drug laboratory in the hotel room.
A crime scene and exclusion area was established.
A 28-year-old man was arrested and taken to Taree Police Station, however became ill and was taken to Manning hospital.
Four police who entered the room also became ill and were taken to Manning hospital for treatment. They have since been released.
The 28-year-old has since been released and was taken back to Taree Police Station where he is helping police with their inquiries.