Mayor of London Sadiq Khan has hit out at ongoing delays into an inquiry over an additional £51m (€56.8m/$67m) that was required to transform the London Stadium into a multi-use venue.

Built to serve as the centrepiece for the London 2012 summer Olympic Games, the venue has since become the home of English Premier League football club West Ham United.

However, a row over the cost of converting the London Stadium so that it was able to stage football matches has been ongoing since it was revealed that the overall price tag was £323m, significantly more than the forecast cost of £272m.

Khan has been pushing for an inquiry into the process in order to establish why the eventual cost was so much higher than estimates, but a formal investigation is yet to begin.

According to the Newham Recorder, Khan is growing increasingly frustrated at the lack of progress and has ordered representatives from accountancy firm Moore Stephens LLP to attend City Hall today (Friday) to explain the delays.

Earlier this week, David Bellamy, Khan’s chief of staff, told the London Assembly budget monitoring sub-committee the meeting will enable Khan’s “frustration and displeasure” over the “repeated delays” to be directly heard by Moore Stephens. Khan appointed the firm to carry out a three-month inquiry in November of last year, but the process is yet to be completed.

Speaking this week, Gareth Bacon, chair of the London Assembly budget monitoring sub-committee, said: “One of the things that is a concern is that this report may lead to findings and conclusions that have an impact on the mayor’s budget proposals for next year.”