Project architect Lord Rogers and Finance Minister Edwina Hart could be called to answer questions about the controversial scheme by the assembly's audit committee.

Lord Rogers could be called to give evidence

Estimated costs for the new assembly chamber building range from �13m to �41m and there have been problems over the cost and design details.

The row reached a head when Lord Rogers' firm was controversially 'sacked' in July by Mrs Hart in a row over costs.

The architect - who originally agreed to a �27m budget - hit back at his treatment and pledged to build the new chamber for �13m.

Lord Rogers is not thought to have submitted a tender of any form for the contract.

His company - the Richard Rogers Partnership - has refused to confirm or deny reports it has jointly entered a bid for the contract with another firm.

Finance Minister Edwina Hart

On Tuesday, committee members said they wanted the two key figures to provide more information.

In his own evidence, the Auditor General, Sir John Bourn, refused to criticise either side in the dispute.

Sir John said there was no evidence that either Edwina Hart or Richard Rogers had sought to mislead anyone.

The auditor general was asked if a written contract for the project would have helped.

But he said there was not enough trust between the parties to get one signed and it was trust which was needed to manage such projects.

Hyett calls Rogers' treatment 'farcical'

The audit committee's chair, Janet Davies, said she would "consider in due course" calling the Mrs Hart and Mr Rogers to give evidence.

The committee also asked for another report from the auditor general on the building row as soon as possible.

The deadline for the latest round of bidding for the new assembly project passed last week.

Earlier this month, Paul Hyett, president of the Royal Institute of British Architects, described the treatment of Lord Rogers over the past 12 months as "farcical".

The chamber plans have come under fire from Conservative AMs, who have questioned the need for a new, costly building.