There is a “pressing need” for a new road crossing of the Thames at Silvertown, according to London Mayor Boris Johnson.

He has backed plans for the so-called Silvertown Link, but says Transport for London does not have the cash to go ahead with construction.

In a series of written answer to London Assembly members, Mayor Johnson also suggested the Woolwich Ferry could be axed.

He said the 122-year-old service could be replaced with a new ferry from Gallions Reach, along the route of the scrapped Thames Gateway bridge.

He also refused to rule out introducing tolls for the planned Silvertown road crossing — which could be a bridge or a tunnel — if it becomes a reality.

He was challenged on his plans for new river crossings east of Tower Bridge by assembly members James Cleverly and Len Duvall at Mayor’s Question Time.

In a written answer to Mr Cleverly he said: “There is a pressing need to provide an additional road crossing at Silvertown to provide greater resilience to the road network and support longer term growth of the surrounding area.

“Although there is some development funding, there is no funding in TfL’s budget for building a new crossing at Silvertown and I have asked TfL to explore a number of options for how this could be funded.”

Responding to Mr Duvall, Mayor Johnson also hinted the Thames Gateway bridge may go ahead in the longer term.

He said: “I have asked TfL to come forward with detailed proposals to improve connectivity further east at Gallions Reach through a new crossing, which could be in the form of a new vehicle ferry as a replacement to the Woolwich Ferry, retaining longer term potential for a bridge in this location provided the problems with previous proposals have been addressed.”

He said he would make further announcements on his plans shortly.