Ken Livingstone faced accusations of "suppressing" the true cost of the Olympics today as a former senior official claimed it could top £20 billion.

The ex-chairman of the body responsible for delivering the Games claimed the Mayor had kept quiet fears about the soaring budget.

Jack Lemley, who was forced out of the Olympic Delivery Authority in October 2006, said he wanted to be upfront with the public that the cost of building the Stratford venues would be vast.

Mr Lemley said that from "very early on," the ODA was working to a cost estimate for the Games of "well over £12 billion" - more than three times the £3.3 billion publicly claimed at the time.

He told the Standard he was not allowed to tell the truth. The revelation will reignite controversy over the mounting cost of the 2012 project, with the official budget now standing at £9.3 billion.

But Mr Lemley said he believed the final cost would be £20 billion, because of the state of the Stratford site. "We were never able to really go public with the full budget," he said.

"That was always suppressed and the Mayor didn't want any significant growth in these budgets because it would create a bigger tax.

"I had advocated telling the public because I felt like the credibility of the process would be eroded ... as time went on and it became evident what the [real] costs are."

Last year Olympics Minister Tessa Jowell announced that the budget had risen to £9.3bn. But Mr Lemley described that figure as "ridiculous" and said he was now "positive" the budget would rise to £20 billion.

Mr Lemley said he was "run off" (forced out) from the ODA because " noone wanted to believe" the figure. "I was deeply concerned about the [ODA] organisation and the lack of urgency and I was worried about the dates - even then we had a desperately short time to do our work," he said.

Mr Lemley said the ODA had not taken sufficient account of "the polluted water issues" and "[a] sewage treatment plant that discharges hundreds of thousands of cubic metres of raw sewage" near the Olympic site.

He said £20 billion "was a figure I held all the time. But nobody wanted to hear it because they'd have to admit that they were culpable for suppressing the data."

Mr Lemley was forced out of the ODA in acrimony after being accused by the Mayor of working with failed Tube consortium Metronet.

In a letter to Tessa Jowell, seen by the
Standard, Mr Livingstone said he could not 'continue to have confidence in Jack Lemley' because he was engaged in discussions with Metronet in a private capacity to seek work from them'.

But Mr Lemley said: "I had been cleared by everyone concerned - I wouldn't have done it otherwise. I think Ken is capable of anything."

An ODA spokesman said: "Jack's view is not shared by anyone working on the project. The Chairman believes the project can be delivered within budget."

A spokesman for the Department of Culture Media and Sport described the claims as "ridiculous," saying: "The budget for 2012 was still months away from being agreed when Mr Lemley left his job as chairman of the Olympic Delivery Authority in the autumn of 2006. It is simply untrue to say that the real budget is £12bn and that this figure has been suppressed."

The Mayor's office declined to comment.

Link to:

Columnists

David Sexton

Cycling has opened my eyes to the city I live in

Dominic Sandbrook

The Emperor who holds up a mirror to our times

Andrew Gilligan

It's not just what the LDA did but what it failed to do

Pick of the blogs

Paul Waugh- Politics

Has David Cameron unwittingly exposed a Tory fiddle?

Mark Prigg - Technology

All over London, a new subculture which tinkers with technology is emerging

Jonathan Prynn- Consumer affairs

W6 has its first Poundland store