London mayor Sadiq Khan has ordered an investigation into the rising bill for converting the London Stadium for use by West Ham amid concerns that taxpayers will be saddled with the costs for years to come.
The Premier League club moved to the centrepiece of the London Olympics this season but it has not been a smooth transition with several incidents of crowd trouble and complaints about a lack of atmosphere.
But Khan, who replaced Boris Johnson as mayor in May, is more concerned about a £51 million hike in the cost of transforming the stadium from its Olympic configuration into a 60,000-seat multi-purpose venue fit for top-flight football.
A spokesperson for Khan said: "The mayor is deeply concerned about the finances of the Olympic Stadium, which __have clearly been left in a total and utter mess by the previous administration at City Hall.
"The former mayor announced just last year that the total cost for transforming the stadium was £272m. In reality this is £323m - a difference of more than £50m.
"Sadiq has ordered a detailed investigation into the full range of financial issues surrounding the stadium.
"We remain committed to the future of the stadium as a venue for football and other sporting and cultural activities, and we are confident that London will host a fantastic World Athletics and Para Athletics Championships in 2017."
When asked for reaction, West Ham chose not to comment.
Khan's investigation will cover all stadium costs but it is the retractable seating system that was installed to get football fans closer to the pitch that is causing the most alarm.
It is understood that the seats are not as "retractable" as the Greater London Authority, the Stratford venue's owner, had been led to believe and they actually take 15 days to remove or replace.
This means extra costs and delays - a major concern when the stadium's business plan depends on concerts and other events during the football off-season.
And Sky News has reported that West Ham could be forced to play on the road for the first month of next season.