The NAO said plans to raise Ј100m as part of a seven-year, Ј700m, private sector package may be hit due to delays in fundraising and sponsor demands.

"UK Sport should avoid distributing too high a proportion of funding to sports with no medal potential," they warned.

"There remains a risk that raising all this money will not be achievable."

After the 2004 Athens Olympics, when the British team returned nine gold medals, UK Sport adopted a "no compromise" policy of focusing funding on sports and athletes with a real chance of success.

As a result, 16 sports are now receiving money from UK Sport for the first time, and only Olympic football and tennis are not given funding.

"Should there be a significant funding shortfall, UK Sport is currently working on a range of contingency plans which it will finalise and discuss with sports following the Beijing 2008 Games," the NAO confirmed.

"It is already too late, however, for UK Sport to protect the full funding it proposes for those sports it expects to win medals in 2012 if the worst case funding scenario should materialise."

Chief executive of UK Sport, John Steele, welcomed the review and said: "We are pleased with the key findings of this report, which gives us real confidence that we are on the right track in terms of our strategy and approach.

"I would like to thank the NAO for their valuable insights and we will take on their thoughts and recommendations and make sure they help us in our continual drive to deliver our twin ambitions for 2012: medal success at the Games and the lasting legacy of transformed and sustainable elite sporting system.

"We recognise too the risks they highlight - in particular the fact that our ambitions are dependent on the full funding package being available."