The backers of the €500m extension to Liffey Valley shopping centre in west Dublin have been told they must provide "affordable start-up retail units as part of the proposed development".

South Dublin County Council has written to Owen O'Callaghan's O'Callaghan Properties (OCP) and the Duke of Westminster's Grosvenor, stating that this is a requirement under the local area plan and they will have to set out the location and design of the units.

OCP and Grosvenor plan to develop a large foodstore, two anchor department stores and 60 retail units at the centre as well as 2,100 spaces in two car parks. The council has told the pair that the "proposed foodstore/ hypermarket" has to be redesigned as it "would not make a positive contribution" to the town centre.

They have also been told that one of two proposed car parks "is unacceptable" in its design and would not fit in with the local area plan and that the traffic impact assessment does not comply with guidelines set down by the National Roads Authority. They will also have to submit a disability audit of the proposed development and plans for public art.

SDCC has told the applicants they will have to redesign a proposed transport hub as it is designed only to deal with buses, which "is not acceptable within an emerging town centre and would not facilitate the delivery of a successful multi-modal transport system at Liffey Valley".

They must also set out plans to upgrade Quarryvale Park in conjunction with the new development and the council is recommending a multi-games area and extended play area be included.

Meanwhile, RGData has objected to the plan, stating that the application is premature because it will attract business away from surrounding areas and "smaller businesses will be decimated" as a result. It questioned the viability of the proposal in the current economic climate and said it was contrary to national transport objectives.

The Liffey Valley centre is owned by Grosvenor and Aviva Investors, who are trying to dispose of part of it.