BBC wasted £100m on refit of Broadcasting House offices

Building work at London base, along with Salford and Glasgow sites, will cost £2bn

The BBC has wasted £100m – enough money to have employed Jonathan Ross on his widely criticised salary for a further 16 years – by overspending on a refurbishment of Broadcasting House, which will now be completed in 2013, four years behind schedule.

The overspend was uncovered yesterday in a report by the National Audit Office (NAO) which found that the project, along with the building of two other BBC facilities in Salford and Glasgow, will cost a total of £2bn.

Amyas Morse, the head of the NAO, said: "The BBC let the Broadcasting House project run into serious difficulties before the governors and then the trust took action and the result is a four-year delay and a cost overrun of £100m."

In its report, the NAO said: "The BBC is not well placed to demonstrate value for money from the £2bn it has committeed to spending on the three projects over their life."

The report puts pressure on the corporation at a time when the BBC director general Mark Thompson is conducting a review of its services and political and commercial opponents are questioning the amount of money it receives from the licence fee.

The redevelopment of the Broadcasting House building in London's Portland Place will now cost £1.05bn, £55m more than originally approved. Delays to the work have incurred a further £52m in unplanned costs.

The new headquarters for BBC Scotland at Pacific Quay in Glasgow will now cost £188m, rather than the originally planned £126m. Mr Morse added that "for future major projects, the BBC needs to make sure that investment decisions are based on a full assessment of the scope and cost of the project".

The Salford Quays project, which will contain five BBC departments including BBC Sport and the radio network Five Live, is expected to cost £76m less than the budgeted £877m when it is completed late next year.

Responding to the report, Jeremy Peat, of the BBC Trust, the corporation's governing body, said: "Serious mistakes were made in the first phase of the Broadcasting House project. Licence fee-payers were let down."