LONDON (Reuters) – The mayor of London is taking control of the former Olympic stadium used by Premier League side West Ham United after an independent review disclosed rising costs and mounting losses.

Mayor Sadiq Khan called the findings “simply staggering”, with projected annual losses of around 20 million pounds, and said West Ham had secured “the deal of the century” from his predecessor, Boris Johnson.

Asked whether the stadium at the heart of the 2012 Olympic Park might be closed, sold or re-tendered, he told Sky News television that he was “exploring all avenues”.

West Ham pay rent of 2.5 million pounds per season for the stadium, which has been co-owned by the London Legacy Development Corporation and the local Newham council.

The east London club, who moved in last year after conversion works, said their contract was watertight and legally binding, and that they remained “absolutely committed to its terms for the entire 99-year duration”.

They also backed the mayor’s actions. Khan, who took office last year, said the situation was not of the club’s making.

“We’re going to work with West Ham, they’re our partners,” he said. “It’s not their fault that they were given such a fantastic deal by the previous mayor. Who can blame them?”

Newham council said it would voluntarily relinquish ownership, writing off an original 40 million pound investment but limiting future liabilities.

Newham Mayor Robin Wales blamed Johnson, now Britain’s foreign minister, for “onerous” contracts that had left the stadium finances in a “dreadful mess”.

A spokesman for Johnson said the mistakes belonged to his Labour predecessor Ken Livingstone and the government of then-prime minister Tony Blair.

“Signing off on a stadium fit only for athletics was a massive mistake. Their catastrophic planning errors lie at the heart of the problem,” he said.

He added that the London Games had nevertheless left “a legacy other past host cities can only dream of”.

The review showed transformation costs after the 2012 Olympics rose to 323 million pounds from a budget estimate of 190 million.

The costs of operating relocatable seating, necessary for the stadium to switch between soccer and athletics, represented the largest annual expense at more than 10 million, a sum more than 300 percent greater than the budgeted amount.