A man charged in connection with an alleged surveillance operation on the Dublin headquarters of a number of specialist garda units has admitted taking photos of the complex after renting a room in an overlooking hotel.

Corey Mulhall, 41, of Daletree Court, Ballycullen, Dublin, was arrested in September 2012 after detectives observed suspicious activity at a hotel close to Harcourt Square.

The Harcourt Square building is home to the Special Detective Unit, whose tasks include monitoring the activities of dissident republicans.

Mr Mulhall has pleaded not guilty to membership of an unlawful organisation styling itself the Irish Republican Army, otherwise Óglaigh na hÉireann, otherwise the IRA on 26 September 2012.

Deirdre Murphy SC, for Mr Mulhall, told the non-jury court that she had been instructed by Mr Mulhall to make a number of formal admissions.

She said that Mr Mulhall wished to admit that on 26 September 2012 he went to the Harcourt Hotel in the company of a man who had offered him money on behalf of another unnamed man, who was in dispute with gardaí, to take photos of a garda who drove a specified vehicle.

Mr Mulhall booked a room in the Harcourt Hotel under the false name "Jason Egan" and requested a room at the front of the building having been initially offered one at the rear.

He brought with him a rucksack containing a number of personal items, including his camera, and between 2.15pm and 4.53pm Mr Mulhall took photos mainly of the right-hand-side of the garda complex on Harcourt Street.

Ms Murphy told the court that there would also be no issue with regard to the arrest and detention of the accused man.

The trial continues on Tuesday before presiding judge Mr Justice Paul Butler.