Hugo Swire, the Shadow Culture Minister, called on the Chancellor to answer questions about the funding as Brown used a school sports visit to declare his pride at the way Britain was organising the 2012 event.

 

Uncertainty continues to hang over the revised Olympics bill, which has still not been published 20 months after London was first awarded the Games.

 

The eventual figure is expected to confirm that the construction bill for the Olympic Park has nearly doubled.

 

Swire today put Brown's role in the spotlight as he called on the Chancellor to explain why he signed off the original budget.

 

Delays in publishing the new budget have sparked anger and frustration among the organisers of the Games, including London 2012's chairman, Sebastian Coe, and its chief executive, Paul Deighton.

 

They believe the political horsetrading in Whitehall has threatened to derail the project and made more difficult their task of raising sponsorship from blue-chip companies for their separate privately funded £2 billionn budget for actually running the Games.

 

A panel of MPs earlier this week ridiculed the original budget of £2.37 billion as "Alice in Wonderland" costings and condemned the delay in publishing updated figures.

 

Edward Leigh, the Conservative chairman of the public accounts committee, described the Olympic bid as a "pig in a poke as far as the taxpayer was concerned".

 

Swire said that the Chancellor should also explain the failure to make inroads in raising £750 million from the private sector to help infrastructure costs, and a further £100 million to help elite athletes.

 

Swire said: "The Chancellor ought to be spending his time sorting out the mess he has made of the Olympics budget.

 

"We need answers to these questions as matter of urgency, as every day that goes by with further speculation about spiralling costs is undermining preparations for the games and the public's confidence that they can be delivered successfully.

 

"Gordon Brown should get a grip on the Olympics budget he approved and sort this mess out now."

 

A Labour spokesman said: "The Conservative party really need to take a leaf out of Seb Coe's book and get behind the non-partisan effort to make the 2012 Olympics a success.

 

"The whole Government is working hard to finalise the Olympics budget.

 

"We will make announcements in the normal way in due course, and we will certainly not be deflected by these pathetic and unpatriotic attempts by the Tory party to undermine Britain's Olympics for the sake of short-term partisan gain."