Residents around Croke Park have claimed the licence for last weekend's U2's concerts was invalid and say they will be reporting Dublin City Council to the ombudsman as a result.

Concert promoter MCD also stands to lose an €80,000 bond after U2 were found to have broken noise-level limits during all three of their shows. Numerous complaints were received by the council afterwards, by phone and in writing.

Although relations between the residents and GAA officials have improved since a blockade of the stadium early last week threatened to disrupt this weekend's All-Ireland football quarter finals, council officials who granted the public-event licence are now firmly in the firing line.

"We will be making a formal complaint about the city council to the ombudsman," Pat Gates, chairman of the Croke Park Area Residents Alliance (CPARA) told the Sunday Tribune.

"Our legal advice is that the whole application itself for the licence to the city council was invalid. MCD broke a number of regulations in relation to planning."

Solicitors acting for the CPARA have objected to the delay in providing crucial information relating to "the removal of structures and the carrying out of any works for the reinstatement of the venue subsequent to the event".

This delay gave members of the public just days to object instead of the statutory period of five weeks, solicitors claim. There are further arguments relating to the immediate laying of a new pitch.

Legal advice furnished to the CPARA states: "While one accepts that the work of re-laying the pitch requires to be done, it does not of necessity require to be carried out in such a short space of time and at such a cost in terms of the extent of disturbance to the local community."

In summary, the law firm says the planning application was invalid and in breach of regulations.

"[It is] contrary to proper planning and constitutes a permission for an environmental pollution in the form of noise nuisance by MCD and Croke Park stadium."

While residents were advised they could have sought an injunction on the concerts based on that legal position, they chose not to.

Dublin City Council said it was satisfied a valid application was lodged but admitted there were issues with sound. "The noise level [of a 75-decibel maximum] was exceeded at all three concerts. Complaints were made to the EHO on site and subsequently to the council," a statement said.

Council authorities are now entitled to hold all or part of MCD's €80,000 bond as a result of this breach.

In relation to the licensing application, MCD said: "We cannot comment on advice given to residents or on DCC practices; however we can confirm that DCC undertook a detailed consultation process that included submissions from residents and other interested parties."