Two separate police investigations are underway as a result of a High Court judge's decision to halt drugs and firearms prosecutions involving 21 members of the Red Devils motorcycle gang.
Justice Simon France last week ruled that police had committed a fraud on the courts by faking the arrest and prosecution of an undercover officer who had had dealings with the gang.
The judge said police acted to protect the undercover officer's street credibility, but in doing so committed a fundamental and serious abuse of court processes.
A police spokesperson says an investigation has begun into the Red Devils operation and issues highlighted by Justice France.
The Independent Police Conduct Authority has also been notified.
The Police National Criminal Investigations group is reviewing the undercover programme to ensure that no further such incidents occur.
Meanwhile, the Crown says it will appeal against Justice France's decision to stop the Red Devils case.
