Campaigners say a two-year delay announced today should be "the beginning of the end" for a controversial road-building scheme.

Opponents of the Lower Thames Crossing, which would link Kent with Essex, have leapt on confirmation from the government it intends to put back construction even if the project is given the go-ahead.

To date around £800 million has been spent on the road link – with costs for the total project confirmed to be rising to £9 billion – and the Secretary of State for Transport has today insisted the government remains committed to the plan.

However, the project will be delayed as ministers "look to rephase construction by two years".

Reacting to this latest development, Laura Blake, chairman of the Thames Crossing Action Group (TCAG), said she believes "this is the beginning of the end for this troubled scheme".

She said: "Rather than delay, the government should put the scheme out of its misery and cancel it for good, rather than continuing to blight people's lives.

"The country cannot afford £10 billion-plus on a project that is not effective or fit for purpose, nor deliverable at a time of climate emergency."

Supporters of the scheme argue the new 14-mile cross-river road route is needed to ease congestion at the Dartford Crossing.

National Highways has said the tunnel would double road capacity across the Thames east of London.

It had been expected that work on the two new 2.5-mile tunnels under the river could start as early as 2024.

In a written statement to parliament, transport secretary Mark Harper said: "To date we have spent over £800 million on planning the Lower Thames Crossing.

"It is one of the largest planning applications ever, and it is important we get this right.

"We remain committed to the Lower Thames Crossing, and the Development Consent Order process will be an important opportunity to consult further to ensure there is an effective and deliverable plan.

"In order to allow time for this process, and given wider pressures on RIS [Road Investment Strategy], we will look to rephase construction by two years."

At the weekend, TCAG re-stated its opposition to the plans as a "smart motorway by stealth".

The government also confirmed it would be cutting parts of the controversial High Speed 2 railway line between London and the north.