London’s new Hungerford pedestrian river crossing may be scrapped after a demand for extra safety measures before work on the scheme can go ahead.

A senior source on the project said: “The design-build contract is now null and void. We are pessimistic about the bridge going ahead.”

The scheme, designed by Lifschutz Davidson, has been on site with joint venture contractor Costain/Norwest Holst since October, but work was put on hold this week.

It is understood that the safety measures demanded by London Underground will mean additional work costing £19m. The publicly funded project had been budgeted at £30m.

A safety sweep of the River Thames in 1996 revealed the presence of two unexploded bombs close to the north side of the bridge and Bakerloo and Northern Line underground tunnels.

LU wants nearby floodgates to be refurbished and work restricted to times when the the Tube system is shut.

A spokesperson for the client, Cross River Partnership, said he could not comment on when work would resume.

He said: “In the post-Paddington climate, LU feels further restrictions are necessary and it is perfectly within its rights.”

The DETR and the London mayor have been approached for the extra cash. CRP says neither has yet confirmed when it would make a decision.

Concerns that the contractor may not be paid were quelled when the CRP spokesman said payments would be made, although he could not confirm when this would occur.