LONDON, July 10 - The British government is financially exposed over the 2012 London Olympics and should put in place a strong monitoring system to make sure preparations do not fall behind schedule, lawmakers said on Tuesday.

Parliament's Public Accounts Committee also complained about a lack of clarity over how Olympics venues will be used when the Games are over, raising the risk that they would not be suitable for their future users.

The government more than doubled the estimated cost of staging the London Olympics in March to 9.3 billion pounds ($18.74 billion). Billions of pounds are being spent on building sports facilities and regenerating a swathe of east London.

Committee Chairman Edward Leigh, an opposition Conservative, said the government's Department for Culture, Media and Sport was ultimately responsible for coordinating the array of organisations involved in preparing for the Games.

"It is worrying therefore that strong arrangements for monitoring progress and managing risk are so far not in place," he said in a statement accompanying the committee's report.

If the timetable for building facilities for the London Olympics slipped, it would heighten the risk that organisers would have to pay more to contractors or would have to lower standards to ensure the Games opened on time, he said.

"This risk must be addressed by establishing suitable incentive arrangements with contractors to deliver quickly, to cost and to the right quality," Leigh said.

The panel urged the government to create a framework to monitor progress and provide early warning of potential problems.

As ultimate guarantor of funding for the Games, the government was financially exposed, the committee's report said.

"In seeking to prevent further calls on public money, the department needs to satisfy itself that the London Organising Committee's costs are under control and its revenues on track, and should develop a plan for doing so," it said.

Fears over spiralling costs have soured the euphoria that gripped the British capital when it was awarded the Olympics.

Britain has a history of delays and cost overruns for major projects such as the Millennium Dome, the centrepiece of Britain's millennial celebrations, and the new Wembley stadium.

The government said in March it would stump up an extra 4.93 billion pounds for the Games and urban regeneration while nearly one billion pounds more would be needed from London taxpayers and the proceeds of Britain's national lottery.

Leigh said that when London was bidding to host the Olympics the government "seriously underestimated the costs of the Games and was far too optimistic about the extent of private sector funding."

Despite the criticism, London's preparations for the 2012 Olympics received a glowing report from the International Olympic Committee during an inspection visit last month.