AIB is challenging developer Sean Dunne's right to develop part of a site he owns at AIB Bankcentre in Ballsbridge, Dublin 4. The bank sold the land to Dunne in 2006 for a reported €200m but it claims he "does not have the legal right or interest to carry out" his proposed development of offices, apartments and shops on part of the site.

The letter, seen by the Sunday Tribune, was sent by consultants RPS on behalf of AIB and requested that Dublin City Council "treat that information as confidential to our client and the applicant, and would not disclose it to any third parties nor include it in on the public file, nor the website, nor any other locations where it is accessible to third parties".

Dunne's plan proposes the construction of six blocks of up to nine storeys on the land at the junction of Merrion Road and Serpentine Avenue.

The letter on behalf of AIB says "covenants and reservations in the deed of transfer transferring the property… specifically and expressly confirm that the… plaza area within the site is to be kept free of development and contain a right of way for our client and its nominees over the plaza area".

It says that Dunne's company, Mountbrook Merrion Road Development, which is seeking permission for the development, is aware of AIB's "concerns and has acknowledged the restrictions contained in the deed of transfer and that they prohibit development of the existing plaza area without our client's consent".

The RPS submission also states that AIB retained ownership of some other land between the plaza area and Merrion Road.

"Again, however, these lands retained by our client have not been identified on the submitted plans and are in fact included in the lands in respect of which the application is being made. We reiterate that our client has not given the applicant consent to make application for development on lands which our client owns," the letter states.

AIB declined to comment last week. Mountbrook had not replied to a request for comment at the time of going to press.

Dublin City Council has delayed a decision on the application until July. It has asked Dunne's company "to submit legally acceptable documentary evidence that they have sufficient legal interest in the whole site to carry out the proposed development with particular reference to the area in the vicinity of the proposed central access route".

Revised designs for the proposal have also been sought by the council.