Olympic stadium conversion costs keep rising – but project's manager insists taxpayers won't foot the bill

Stadium confirmed the cost of the deal will rise by £35.9m after signing initial £154m contract

The cost of converting London’s Olympic stadium into a new home for West Ham United has jumped by nearly £36m but taxpayers will not foot the extra bill, the stadium’s managers insisted today.

Struggling builder Balfour Beatty signed a £154m contract to transform the venue in January, but underestimated the challenge of installing the largest single span cantilever roof in the world.

The company has been in talks with E20 Stadium - a joint venture between Newham Borough Council and the London Legacy Development Corporation - over increasing the value of the two-year contract.

E20 Stadium confirmed that the cost of the deal will rise by £35.9m as support for the new roof has “required significantly more strengthening work” to the main roof truss, which was originally due to be taken down after the Games.

A spokesman added: “We will meet these costs from the project contingencies and additional income we will generate from our other developments. There will therefore be no additional call on the taxpayer and no impact on our current programme.”

The stadium is due to host five matches during next year’s rugby World Cup, while Premier League club West Ham United will move in from 2016. The venue will also be the new national competition stadium for athletics in the UK.

For Balfour the extra cash will come as a relief after a string of profit warnings and a collapsed merger with smaller rival Carillion.

The firm has drafted in KPMG to carry out a forensic review of its troubled UK construction arm after reporting an extra £75 million in write-downs on troubled construction projects, while a new chief executive - Qinetiq’s Leo Quinn - joins in January.