Environmental campaigners have stepped up their pressure on the Mayor of London over the controversial Silvertown Tunnel.

An open letter penned by councillors, activists, environmental experts and campaigners on both sides of the Thames has this week been published.

The coalition of academics, politicians and campaigners from Stop the Silvertown Tunnel Coalition have written to Sadiq Khan asking him to cancel the proposed £1bn tunnel connecting Greenwich to Silvertown.

The letter reads: “We are concerned that allowing TfL to build the Silvertown Tunnel would threaten much of your good work on improving air quality, and position London’s carbon emissions on a pathway that is not consistent with the Paris agreement and contributes directly to climate breakdown.

“We are a cross-party coalition, and we are not opposing the Tunnel to make a political point, but because we believe both the environmental case and the economic case for the project are deeply flawed.”

It comes following TfL being suspended from signing off on the tunnel after one bidder, Silver Thames Connect, legally challenging the contracts awarded to Riverlinx earlier this year.

STSTC and Greenwich mother of three, Victoria Rance, says: “We are very glad the procurement process has been paused.

“It will give Mayor Khan and his advisors a chance to take another look at the evidence that shows that this scheme is a massive economic and environmental mistake that would end up defining his term as Mayor.

“According to TfL’s own figures, the Silvertown project will increase traffic, increase carbon emissions, and worsen already serious local air pollution. There’s no way for him to justify spending £1bn of SE London residents’ money on a major new road in a climate emergency.”

Pressure has mounted for a rethink on the tunnel with local councils, such as Hackney, appearing to side with campaigners.

Greenwich has historically supported new river crossings and is backing the new road despite local Labour branches passing motions for leadership to change stance.

Supporters of the tunnel say it will cut congestion at the Blackwall Tunnel, which is closed hundreds of times a year.

The tunnel will have a lane for public transport, which backers say will play a key role in driving pollution down.

A spokesman for the Mayor told the Local Democracy Reporting Service today: “The Mayor has put tackling the climate emergency at the heart of his work as Mayor. That’s why when Sadiq became Mayor, he worked with TfL to make significant changes to the Silvertown Tunnel scheme to better protect the environment and ensure there is a greater focus on walking, cycling and public transport.

“The Silvertown Tunnel will tackle congestion, reduce idling cars standing in traffic, and importantly increase cross-river bus services. Bus crossings are currently severely restricted by the Blackwall Tunnel, built over a 100 years ago.

“Plans for the Silvertown Tunnel have a clear focus on cleaner transport, with buses using the tunnel expected to be zero emission from launch, and the crossing being located within the extended Ultra Low Emission Zone.”

Delays in seeking consent to build the tunnel have seen its opening pushed back from 2023 to 2025.