Gordon Brown has faced questions over his responsibility for the spiralling costs of the London Olympics.
The Liberal Democrats accused the Chancellor of approving open-ended budget commitments for the 2012 Games and criticised his VAT rules.
Their intervention follows Culture Secretary Tessa Jowell's admission last week that the estimated cost of the Olympics had risen from £2.375 billion to £3.3 billion.
Treasury spokesman Vince Cable has now tabled a series of parliamentary questions in a bid to pinpoint which ministers and officials were involved in budget decisions for the Olympics.
Mr Cable said: "Costs have clearly been massively underestimated.
"The Chancellor accepted the International Olympic Committee requirement to give a Government financial guarantee. We need to know what checks he made before making this commitment."
MPs are concerned that Londoners may face council tax increases to meet the rising costs, which are due in part to an unforeseen VAT bill on construction costs.
"There is particular confusion over the Treasury's role in taxation," Mr Cable went on.
"Ministers have said that there would be favourable tax treatment for the Games but no one appears to have realised that this had major implications for the VAT status of the Olympic delivery vehicle.
"Hundreds of millions of pounds of taxpayers' money is at stake. I am pressing for a clear explanation of precisely what role the Treasury and HMRC have played."
