Welsh political leaders have backed a decision to spend £41 million on the new assembly building in Cardiff.

First minister Rhodri Morgan, Plaid Cymru leader Ieuan Wyn Jones and Liberal Democrat assembly leader Mike German have all supported the decision to invest the cash.

The three men put their name to a motion supporting a lump sum contract for the new building with Taylor Woodrow Construction at a cost of £40,997,000 before VAT.

But the Conservatives dissented from the move, calling for not more than a nominal £1 to be spent on the new building.

Amendments to the motion tabled by the Conservative business manager, Jonathan Morgan, said that improving public services should take priority.

"After repeated rises in the cost to Welsh taxpayers of the new assembly building, we are now looking at a minimum cost of £55 million," Morgan warned.

"Bearing in mind recent and recurring rises of waiting lists in Wales, should the assembly government not have more pressing items on its agenda rather than feeding its own ego?"

He added that the new building was proving "a monstrous waste of money", with even a small scale display model costing £100,000."This merely serves to show the arrogance and ineptitude of assembly ministers who are simply interested in feathering their own nest," Morgan said.

But with the new building set to proceed as planned, the Lib Dem assembly leader said that the open design of the new building should prompt a "spirit of openness" among AMs.

"Most people do not go in to the Palace of Westminster because it is not the most inviting building to get into," argued German.

"This is in stark contrast to the openness of our proposed new chamber building.

"You will be able to see right through it, and it will be as open to the public as can possibly be achieved within the constraints of security advice."

He said that the architecture was a reflection of the democratic purposes of the devolved assembly.

"Let's not blot that aspiration by closing ourselves off from both the press and the public," German warned.

And he said that both the public and the media should have free access to assembly members.

"As we take this final decision we should not be hindered by short sightedness. This is an enduring building - it is one which will stand as a symbol of our nation. It is the right decision for Wales," German added.