The largest development ever proposed in Ireland has been stalled by Dublin Corporation planners.

The £1.03bn Spencer Dock development, which features a £90m conference centre designed by leading US architect Kevin Roche, has fallen foul of the planning department's city manager. Developer Treasury Holdings has been told that significant changes must be made to the overall design.

A spokesman for the planning department said the Roche-designed National Conference Centre was "reasonably accepted" by planners, but the scale of the surrounding development, which the developer insists is necessary for the centre to be viable, had to be slimmed down.

The spokesman said: "The number of the buildings in the scheme must be reduced. The bulk and height of the buildings is also excessive for a low-rise city like Dublin.

"The tallest building is 95 m and other blocks are 17 storeys high. The proposed 7000-space car park must also be reduced as it would put excessive strain on the road network."

The conference centre has been awarded a European Union grant of £22m and is due to be completed by January 2001. Speculation is mounting that the funding will be withdrawn if construction is not started by June.

The spokesman added: "There is a danger that the scheme could lose EU funding because of the delay, but this is the biggest development ever in Ireland and its complexity warrants serious consideration."

Treasury Holdings was unavailable for comment.