Project's second phase in doubt as mayor and government at loggerheads over £30m shortfall

A major rail project in south London has become embroiled in a funding row that threatens to undermine the scheme.

The extension of the East London line between Surrey Quays and Clapham Junction is facing a £30m funding shortfall, throwing the second phase of the development into doubt, according to the Evening Standard.

London mayor Boris Johnson has said he will provide no more than £15m in extra funding and has written to the government urging it to provide the outstanding cash.

In a letter to transport secretary Geoff Hoon, Johnson wrote: “I urge you to agree to this £15.5m contribution at the earliest opportunity.”

But the government said it had already given Transport for London (TfL) a “generous” funding package for the next 10 years and saving the scheme is up to Johnson.

A spokesman said: “The government is already providing more than half of the funding needed for phase two of the East London line extension. We have already agreed a generous long-term funding settlement with Transport for London worth around £40bn over the next 10 years.

“It is now for the mayor and TfL to decide on their priorities for transport investment in London.”

The cost of the whole scheme is estimated at around £110m, with capital costs of £75m.