Bono's home extension plans have hit a glitch after an influential heritage group claimed they would "distract" from fellow singer Enya's historic mansion.

An Taisce made the observation on the U2 frontman's planning application for his Vico Road property in Killiney.

The submission was made to Dun Laoghaire Rathdown Co Council at the last minute before the date for objections had passed.

It means that, even if the council grants permission for Bono's revamp, An Taisce is entitled to appeal against the decision to An Bord Pleanala, delaying the project for months.

The heritage group contends that Bono and his wife Ali Hewson's house -- Temple Hill -- is within a conservation area.

It says the extension would distract from two protected structures -- Enya's Ayesha Castle and Killiney Hill Obelisk.

An Taisce adds that "a more sympathetic extension [to Temple Hill] with a similar design and finish to the original house should be considered".

The planning application revealed the rock star reviewed a proposal to tear down his Killiney mansion and construct a new house but that he rejected this idea.

He and Ali decided demolition would be inappropriate and were "keen to retain the existing building".

The details were contained in a letter by his architect Colin Jennings to the county council.

Bono and Ali have applied to add a completely new second floor, including an en suite master bedroom and his and her wardrobes -- to their home.

The couple also want to add a lower ground floor conservatory to the house.

The proposed conservatory will be accessed through the kitchen and living room.

Bono, who has applied to the council using his real name, Paul Hewson, is seeking to have a terrace at second floor level around the full perimeter of the house.

If permission is granted, the changes will make the most of the U2 singer's amazing views.

The plans show that the terrace will be accessed through a new en-suite master bedroom as well as an adjoining en-suite study.

Posted on the council's website, the drawings reveal that the superstar is making provision for considerable wardrobe space.

The new second floor is to take the place of the existing pitched roof.

A decision by the council is due on or before November 26.

Mr Jennings also pointed out a previous proposal from the couple to construct a three-storey extension was granted permission in 2003.