Robert Firth warned companies to think about the contract

Projected costs for the flagship chamber building - due for completion in 2003 - were found to have ballooned from �27m to up to �47m and Ms Hart decided to put the build out to tender to seek a cheaper price.

CIC Wales chairman Robert Firth said: "I feel Welsh architects shouldn't take this on until they have spoken to Richard Rogers and looked very carefully through the design.

"I hope they will be very cautious. I hope they think through the process before they actually step into line.

"I hope they think about the ethical and the practical reasons behind it."

The CIC is a representative forum for the construction trade, representing over 350,000 professionals and 19,000 firms. It encourages clients to seek value for money.

Partnership dropped

Assembly members voted in July to drop the Richard Rogers Partnership as builders but retain the RRP design.

Ms Hart said she was acting to protect taxpayers' money. She claimed the scheme could not be completed within the promised �24m budget mark due to "significant underestimates in the cost plan prepared by RRP."

Richard Rogers was sacked as the chamber builder

In a bitter exchange, Lord Rogers branded the assembly's management of the project a "catastrophic failure."

The construction was put on hold soon after builders began work on the development in Cardiff Bay.

A spokesperson for the assembly said it would be inappropriate to comment after the CIC's warning because negotiations were ongoing.

In a recent interview, First Minister Rhodri Morgan said he wanted the Rogers-designed plan to be built, but not at any price.