Dublin City Council has thrown out new enlarged plans for the former Chester Beatty Library site on Shrewsbury Road in Dublin 4.

The long running campaign by O'Malley Homes to develop the prime one-acre site on Shrewsbury Road continues with the council's decision to turn down O'Malley's fifth planning application for the site, which the developers bought for €9.14 million in 1999.

Despite having secured planning permission to build seven apartments on the site last year, the Galway developers had sought permission from the council to build a revised and enlarged apartment scheme.

In the new proposals, O'Malley was seeking to change three ground floor apartments into duplex units.

These would be accommodated by adding an extra floor, resulting in around 750sq m (8,072sq ft) more floor space.

Dublin City Council refused O'Malley's plans on the grounds that an in-fill development should be subordinate in mass, size and scale to the established buildings in the area.

While an earlier plan for the site resembled a large, or very large house, in architectural terms, according to Dublin City Council, the current plan resembles an apartment block.

"The current proposed structure is not only too massy; it is materially different in appearance, architectural approach, height and detailing from the previously acceptable building.

"With this additional floor, apparently compressed floor heights and multitude of windows in the roof pitches, it presents itself as an apartment block and does not sit comfortably within the surrounding architecture."

The increased roof height and the increased number of windows will be injurious to the residential amenities of the adjoining houses, the council added.