Mr Armstrong said the building size was increased

Bill Armstrong, the parliament's project manager from the outset until 1998, said the problems came later, in the time of former Presiding Officer Sir David Steel and other MSPs.

Mr Armstrong's comments came after current Presiding Officer George Reid claimed that the die was cast when Mr Dewar agreed a 'pay as you go' deal for the building of the parliament back in 1997.

However, the construction expert said the problems really began when the size of the planned building increased when Sir David was in office, as MSPs demanded more accommodation.

He said this should have led to an extensive review of the project, at the very least.

Mr Armstrong told BBC Scotland: "The allegation that Donald Dewar is totally responsible isn't compatible with the decisions taken by the first presiding officer and presumably MSPs, when in mid-1999 they virtually doubled the size of the project.

"But they continued with the site and the construction management process, which at that time should have been completely reviewed, and the construction management contract possibly terminated."

There must be somebody who was there to say 'look Sir David what you are doing means the cost is at large and the program has gone totally out of the window' Bill Armstrong

And he revealed that when he left the project in 1998, a replacement was not employed for over 18 months.

"It is my understanding that the project was managed 'in house' by the civil service members - none of whom had any construction expertise on the level that this project demanded," he said.

Mr Armstrong called for the role of civil service in the case to be examined.

"There must be somebody who was there to say 'look Sir David what you are doing means the cost is at large and the program has gone totally out of the window'," he said.

Inquiry ordered

His view that the demands of MSPs played a large part in the cost increase was backed by Glasgow architect Gordon Murray who said the original brief was too basic to price the job properly.

Mr Murray added that his company, which took part in the original design competition, did not believe the �40m price tag which was put on the building at the outset.

"When we started analysing the brief our view was that the cost at that stage was probably closer to �90m.That again was for a brief suggestive of a building rather than the building it turned out to be once MSPs were elected," he said.

Sir David told BBC Scotland he did not wish to get into a debate with Mr Armstrong, who had left the project long before it was handed over to the parliament.

The Scottish Executive said an inquiry by current First Minister Jack McConnell would consider questions like these.

Sebastian Tombs, of the Royal Incorporation of Architects in Scotland (RIAS), said that inquiry should not be rushed.

He said: "It won't be completed until after the building is completed and I think that would be a much better result.