Transforming the Olympic Stadium must not cost taxpayers more money—especially now West Ham has been named the preferred bidders.

That’s the demand of a London Assembly report warning that the Legacy Development Corporation is exposed to financial risk that may increase pressure to provide extra public cash.

The Assembly’s Budget committee fears that ambitious legacy plans aimed at rejuvenating east London may be eclipsed by a short-term need to raise capital from high-value housing developments.

Budget chairman John Biggs, whose east London constituency includes the Olympic Park, said: “We need a guarantee from the Mayor that taxpayers will not be left to pick up the bill.

“The once-in-a-generation transformation of the Olympic Park is a huge opportunity for east London—but doesn’t come without financial risk.”

The committee’s Pre-Budget report also wants to know the implications if bus and train fares rise only by inflation rather than ‘above’ inflation as announced, and wants assurances that plans to reduce police costs are judged against changes to policing capacity. The Mayor is expected to publish his Budget early in January.