A Garda investigation has been launched into allegations surrounding surveillance at the Irish Prison Service.

It comes after Justice Minister Charlie Flanagan ordered an 'urgent investigation' into the allegations on Thursday.

That followed on from a report that a serving prison officer claimed covert surveillance, including tracking devices on vehicles, was being used in an effort to detect the smuggling of contraband into prisons.

According to the Irish Examiner, the claims were contained in a sworn affidavit given to the justice minister and the prison service this week by a serving officer.

In a statement, An Garda Síochána said: "An Garda Síochána are examining matters that it is aware of relating to the Irish Prison Service that are in the public domain".

The Irish Penal Reform Trust (IPRT) has expressed "serious concern" over the allegations, and has called for the investigation to be widened.

On Thursday, the IRPT said: "IPRT welcomes the minister's announcement that the Inspector of Prisons, Ms Patricia Gilheaney will carry out a preliminary investigation, which will establish whether there is a need for a formal inquiry.

"However, IPRT emphasises that additional resources must be made available to the Office of the Inspector of Prisons to ensure this investigation can be undertaken alongside its regular programme of work.

"IPRT has consistently raised its concerns that the Office is not adequately resourced."

It was also concerned that under the s.31 statutory investigation, Minister Flanagan "will retain the power to omit any matter from any report where he is of opinion that its disclosure may be prejudicial to security, contrary to the public interest, or may infringe the constitutional rights of any person."

It said: "For that reason, IPRT is also calling on the Data Protection Commission and the Complaints Referee under the Criminal Justice (Surveillance) Act 2009 to consider using their powers to work with the Inspector".