Police in Papua New Guinea suspect rogue immigration officers are part of a crime syndicate producing fake visas and passports.
The Post Courier newspaper reported the Police Fraud and Anti-Corruption Directorate had asked the Immigration Authority to launch an internal investigation.
It followed the arrest of an Australian woman in possession of a fake visa baring genuine stamps and labels.
Chief superintendent Matthew Damaru said six senior immigration officials will conduct the internal probe to run concurrently with a criminal investigation.
Immigration Minister Westley Nukundj said the crime syndicate may contain current and former immigration officers who pose a serious threat to national security.