London Mayor Sadiq Khan has ordered an investigation into the cost of converting the Olympic Stadium into West Ham’s new home.
The move comes as it was revealed the conversion costs have jumped by another £51m to £323m from £272m.
Balfour Beatty was in charge of converting the stadium under a £190m contract.
The Enquirer first revealed two years ago that the costs were going to bust the original budget
Balfour was granted extra cash for construction work pushing the overall conversion cost to £272m.
But Sky News has now learned the price has risen again with the higher costs being partly blamed on extra outlay for retractable seats.
Deputy Mayor Jules Pipe told Sky News: “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.”
When Balfour was granted an extra £36m for the work in October 2014 the authorities said the increase “reflects the huge scale of the works undertaken to transform the former Olympic venue from a temporary athletics stadium into a year-round multi-use arena capable of delivering world class sporting and cultural events.”
The LLDC said: “The stadium work included the removal of the original roof and light paddles and installation of a new permanent roof, the largest of its kind in the world.
“The 45,000sqm cantilevered roof needed significant strengthening of the superstructure to support the 8km of cable net, 112 steel rafters, 9,900 roof panels and 14 light paddles each weighing 45 tonnes.
“The new roof covers every seat in the venue, improving the acoustics and spectator experience.
“An innovative retractable seating system required the removal of the lower seating bowl. The 21,000 movable seats bring the fans close to the pitch for football and rugby ensuring the Stadium has a long-term legacy.”