The British Foreign Office has confirmed that serving PSNI officers have provided training to the Libyan police force over the last year.
The news has caused widespread anger within the Unionist community, given Libya's past links to the IRA.
The policemen were seconded to the UK's National Policing Improvement Agency and travelled to Tripoli after requests from the British Foreign and Commonwealth Office.
In a statement, the PSNI says the North's Policing Board had been informed about the request in December 2008 and approved it the following month.
The PSNI insisted it was satisfied that all appropriate processes were followed and approval received over the deployment to Libya.
The revelation comes in the wake of the controversial early release of the man found guilty of the 1988 Lockerbie bomb which killed 270 people.
Abdelbaset Ali al-Megrahi was released from Scottish prison last month on compassionate grounds.
The move prompted renewed calls from the relatives of victims of IRA violence seeking compensation from Libyan authorities.
During the Troubles Libya provided explosives and weapons to the IRA.