The £9.3bn London Olympics budget contains ‘significant areas of uncertainty’ that could drive costs up, the National Audit Office is to warn today. Financial Times

The government’s dramatic increase this spring in the budget for the 2012 games, almost tripling the original £3.3bn cost to the taxpayer, has put the event on a ‘firmer financial footing’, says a report by the government watchdog.

But Sir John Bourn, head of the NAO, warned of areas of uncertainty affecting costs, including the design specifications and future use of the Olympic venues, the level of price inflation in the construction sector and the contracts negotiated by suppliers.

This high level of uncertainty explains why Gordon Brown insisted the revised budget had to have a £2.2bn contingency fund.