London Mayor Sadiq Khan is facing increasing opposition from members of his own party over plans to push ahead with a new road tunnel under the River Thames.

The Silvertown Tunnel is a £2 billion project that will connect the Greenwich peninsula with west Silvertown by an underground road tunnel that aims to reduce congestion from the existing Blackwall Tunnel.

But critics claim that traffic will only increase once the Silvertown Tunnel is completed, which will have a negative impact on air quality.

Four Labour councils in London have now written to the mayor to call for the project to be scrapped, and 28 motions have now been passed in Labour branch and constituency parties across London calling for the same thing.

That is in addition to four Labour MPs, including Shadow Minister for Climate Change Matthew Pennycook, who have also called for the project to be scrapped.

Hackney, Newham, Lewisham and Southwark councils have all passed motions against the tunnel, with the Mayor of Hackney calling it “fundamentally incompatible” with the borough’s plans to tackle poor air quality.

Labour for a Green New Deal (LGND), the network of Labour activists pushing for green policies, has also joined the campaign against the tunnel and has called on Sadiq Khan to cancel the project.

Lauren Townsend, a Labour councillor and LGND spokesperson, said: “Building a massive road tunnel with a dedicated lane for lorries can never be part of a credible Labour policy on fighting climate change. Party activists across London are calling on Labour Mayor Sadiq Khan to cancel this polluting project before it’s too late.”

The South East London branch of LGND has said that Labour “cannot be credible on green issues” at the London level while continuing to push ahead with the “polluting tunnel”.

Izzy Hickmet, a teacher and SE London LGND campaigner, said: “Sadiq Khan made the right decision when he cancelled Johnson’s vanity project, the so-called Garden bridge. Now Labour members all over London are urging him to think again on the Silvertown Tunnel – which is another Johnson project.

“Sadiq Khan has a prime opportunity to show his green credentials in action. Given that Sadiq Khan has done so much to try to lower air pollution in the capital, it is puzzling that he’s backing a project that will negate the good work he has done so far.

“As Labour campaigners, we are concerned that the party cannot be credible on green issues if its representatives at the London level are pushing a polluting tunnel with a dedicated HGV lane. It just doesn’t make sense and would be tragic if this was Labour’s legacy – to be paid for in health consequences and damage to the environment for decades to come.”

But the Mayor of London has defended the project and stressed the “urgent need” for another river crossing in the area.

A spokesperson for the Mayor of London said: “Anyone who has ever been caught in traffic due to a problem in the Blackwall Tunnel will know that there is an urgent need for another river crossing in this part of London. Extensive modelling shows that the introduction of tolls on both tunnels at Silvertown and Blackwall will mean no overall increase in traffic and an overall improvement in air quality.

“The new tunnel will mean fewer idling vehicles and better local bus services, including double deck zero emission buses that currently can’t operate across the river because of the restrictive size of the Blackwall tunnel.”