Confidence in the 2012 London Olympics is "ebbing away" amid rows between ministers and the city's mayor about funding, the Lib Dems have said.
Culture spokesman Don Foster said he wished those involved would "shut up" until the budget was finalised.
Culture Secretary Tessa Jowell has said the cost of the Games will rise by £900m to £3.3bn.
But London mayor Ken Livingstone called it a "mistake" to give a figure before the budget is published next spring.
The government has insisted the Olympics will be a success.
Last week, Ms Jowell told the Commons culture, media and sport committee that the expected cost had risen 40% from £2.4bn since the right to stage the Games was won in July 2005.
'Ludicrous situation'
The extra £900m was likely to be funded by London council tax payers and lottery funds, she suggested.
But Mr Livingstone said any increased costs were to do with infrastructure for new homes and that Ms Jowell had failed to take into account changes which had cut back the overall bill
Mr Foster told GMTV: "There's this ludicrous situation we're got into with all these figures flying around.
"We haven't got a finalised budget, so everybody's speculating.
"Different government departments are arguing with each other and so nobody knows where we stand. And confidence in our ability to deliver the Olympics is sadly ebbing away when it's going to be fantastic.
"We should be celebrating it; I wish people frankly would shut up."
Council tax surcharge
A row over the size of an Olympics contingency fund and an unexpected VAT bill have not yet been resolved.
The Olympic Park is being funded publicly, through a £20-a-year surcharge on each of London's council tax payers for 12 years, and the National Lottery.
Regeneration is being funded through central government, while staging the Games is being privately funded.
The Lib Dems and the Conservatives have said Parliament needs to scrutinise the costs - which they expect to rise further.
A revised financial plan is expected early next year.
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