UK Sport performance analyst Peter Keen believes Britain needs twice as many full-time coaches if it is to achieve its targets for the 2012 Olympics.
Lord Moynihan has set high targets for Britain at the 2012 Games
British Olympic Association chairman Lord Moynihan says fourth place in the medals table is achievable, but Keen says that would require major funding.
He told Five Live: "Developing Olympic champions is like training doctors.
"It's expensive, takes time and needs real expertise. If in two years' time we've not delivered them, we'll fail."
Keen, who is responsible for planning British success at the London Olympics, added: "Finding talented people and taking them through to the podium is an eight year process.
"We can possibly reduce that to six, but we cannot dream our way to the top of the podium."
Lord Moynihan insisted fourth place in the medals table was achievable with the right funding.
He said: "I don't think we can topple China, the US or Russia, but fourth is achievable within six years if we are properly financed.
"Coaches are our centres of excellence and we need to make sure we have consistent, strong funding from now through to 2012.
"My first priority has been to get this financing plan brought before the Olympic Board by 8 December.
"We're on target to do that but it has to be significantly higher than where we are now."