Opposition is mounting to proposals for two new Thames river crossings in east London because of mounting costs and fears of “mounting pollution”.

The Beckton proposal has shot up by £18 million, London Assembly members have been told, while campaigners fear the Silvertown Tunnel scheme two miles to the west would add to pollution they claim already breaches EU limits.

The Beckton crossing at Gallions Reach linking east London to Thamesmead is now estimated to need £150m till 2020, compared to TfL’s previous 2012 business plan estimate at £132m. A bridge rather than a tunnel would be even more, stretching to £400-£550m.

But this doesn’t include new approach roads to connect the crossing to existing highways either side of the river, Assembly members point out.

The Assembly’s Darren Johnson has called on TfL to keep the existing Woolwich Ferry instead, which connects the North Circular and South Circular routes.

“It would be crazy for the Mayor of London and TfL to push for a Gallions Reach crossing,” he said. “This would need hugely expensive new roads that would generate more pollution and more traffic in one of the dirtiest parts of London.”

He wants both vessels operating the Woolwich Ferry service to be replaced when they reach the end of their lives, which would be £50m cheaper, rather than scrapping them. A final decision on the Woolwich Ferry is being taken next summer.

Meanwhile, a public meeting is being held next week in a bid to stop the alternative Silvertown Tunnel proposal, connecting the Royal Docks to the Blackwall Tunnel approach at North Greenwich.

Members of the ‘No To Silvertown Tunnel’ campaign attached tubes to lamp-posts in the summer to measure the nitrogen dioxide along the Blackwall Approach and found air pollution levels “broke European limits”.

Campaign organiser Chris Taylor said: “The Silvertown Tunnel will blight lives on both sides of the Thames. But few people seem aware of the consequences or that there are even plans to build it.

“The Blackwall Tunnel is London’s biggest rat-run with traffic avoiding the tolls at Dartford.”

The public meeting is being held at the Forum at Greenwich centre in Trafalgar Road, Peckham, at 7pm next Wednesday, October 16.