George Reid, the parliament's presiding officer, said Benedetta Tagliabue had failed to meet a deadline relating to fees.

Mr Reid's comments were made in the first of a series of monthly reports aimed at keeping MSPs and the public up to date on work on the Holyrood building.

Mr Reid said he had been "reassured" that the estimated final cost of the delayed project remained at �373.9m.

His letter to the finance committee said negotiations with the main firms aimed at capping consultancy fees were "well advanced".

But he singled out Ms Tagliabue's Spanish firm EMBT for failing to meet Monday's deadline to respond formally to the parliament's proposals on the issue.

"I am determined to continue to apply pressure on this matter in order to protect the public interest," Mr Reid said.

Debating chamber

The report reveals that problems with glazing have meant there there are no guarantees the new building will be finished by the end of the year.

This relates specifically to the parliament's committee towers and the debating chamber.

Difficulties have arisen in drawing up a timetable for the work that suits both the glazing contractors and other building firms working on site at the same time.

Reports warn of further building delays

Mr Reid said: "On programme, Bovis continue to work hard on our behalf to secure the best dates for completion across site.

"In particular they are focussing on the work of Drawn Metal and Mero, two of our specialist glazing contractors, and Bovis staff have been directly seconded into these companies' teams on site to secure comprehensive programme information by August.

"The drive now is to close out areas of the complex in turn, which will allow an efficient move down to Holyrood. I am reassured to see that work to enable that move is expected to begin in December.

"We continue to focus on completion across Holyrood, and I look forward to the work of devolution beginning to bed down in the parliament's permanent home."

A spokesman at EMBT's Barcelona headquarters said the company could not comment on the report.