The cost of converting Stratford’s Olympic Stadium has increased by £51m, prompting an investigation by the mayor of London.
Costs have soared to £323m from £272m on the scheme, with problems around new retractable seating being a major factor behind the rise, according to Sky News.
The stadium is now home to West Ham Football Club, which signed a tenancy agreement in 2013.
The cost of installing the seats, which have been fitted to improve the view for football fans, is estimated to increase to £8m from £300,000.
Engineers working on the project told Sky News that rectifying the issue could take 15 days at the end of the football season and 15 days to put them back after the summer.
This could threaten the viability of the stadium’s summer schedule.
Mayor Sadiq Khan has now ordered an investigation into the cost increase.
Deputy mayor Jules Pipe said: “Last year the previous administration told the public that the costs had risen in total to around £270m. The new mayor has now been told that cost will be over £320m.
“Understandably, Sadiq has ordered an investigation as to why those two figures are so wildly different.
“As the new administration at City Hall clearing up the mess of the previous administration, we need to make sure that the stadium runs on a sustainable basis and it is affordable to London.”
This is the latest cost increase on the project, after Balfour Beatty’s £154m transformation contract – awarded in January 2014 – increased by £36m to £189.9m in October 2014.
The recent cost of converting the stadium takes the total cost to £752m, the majority of which has been paid for by the taxpayer apart from a £15m contribution from West Ham.