Proposed new river crossings to Beckton and Silverton will “degenerate” the community and cause untold environmental damage, green activists have warned.

Friends of the Earth (FoE) and transport charity Sustrans have attacked London Mayor Boris Johnson’s aim of building a new tunnel under the Thames to the Greenwich Peninsula by 2021.

A Transport for London (TfL) consultation, which ended on March 5, also proposed starting a new ferry service from Gallions Reach in Beckton to Thamesmead by 2017. Both schemes depend on funding and planning permission being securing.

A meeting was hastily arranged by FoE at the Britannia Village Hall in Silvertown last Wednesday to raise awareness of what the group believes would be the damaging effects of the crossings.

It wants more investment in cyclist and pedestrian-friendly infrastructure.

Foe London campaigner Jenny Bates said: “Studies have shown that if we build new roads, you generate more traffic and you end up with congestion across the whole area. That’s not good for businesses or residents.

“The consultation is very unsatisfactory. It doesn’t go into any of these issues.

“It’s hard to say if we changed people’s minds but they were obviously intrigued. This will degenerate and not regenerate the area.”

TfL said the plans would ease pressure on the Blackwall Tunnel approaches.

Director of planning Michelle Dix said: ““A new road tunnel and new vehicle ferry crossing would meet this growing demand whilst strengthening this area’s economic growth.”