A link road has been given the financial backing of the government, which will partly fund the multi-million pound scheme.

The 3.9-mile (6.2km) Norwich Western Link would connect the Northern Distributor Road (NDR) to the A47.

County council leader Kay Mason Billing said she was delighted the government was showing its confidence in Norfolk.

Opposition councillors said the news was “disastrous” and the plan was still in “serious doubt”.

The government has given its approval of the outline business case for the road, which the Conservative-led county council said would cut traffic congestion, reduce journey times and improve air quality in communities.

The announcement means the council can finalise its work on the planning application documents.

“It enables us to complete this long overdue ring road around Norwich and unlock further opportunities for economic growth – providing more of the high skilled, well-paid jobs that Norfolk needs,” added Ms Mason Billing.

“It’s a great example of how Norfolk stands ready to deliver ambitious projects and we look forward to further government support, a fairer share of national funding and to unlocking our great potential.”

Graham Plant, cabinet member for highways, transport and infrastructure, said it was the news “we’ve been waiting and pushing for”.

The financial commitment from the government could bring £231m into the county, he added, with the potential of further contributions.

Conservative MP Jerome Mayhew said the announcement represented major government investment for his Broadland constituency and the wider region.

The council has so far spent £38m on the project’s business plan and preparatory work.

Earlier this year, Labour councillors warned the final construction cost of the link road, estimated at £251m, could rise to £400m once long-term borrowing was factored in.

“What we are seeing is the promise of something that can’t be delivered until after a general election,” said the Labour leader at the council, Steve Morphew.

“I doubt frankly that it’s going to happen. I treat it with serious doubt.

“All the environmental issues that have been flagged and not properly explored have been very controversial, and would need to be overcome.

“I would rather see the development of an integrated public transport system that served all of the county rather than four miles of expensive, environmentally damaging roads.”

Green councillor Jamie Osborn said the announcement was disastrous news for taxpayers and the environment, with the council potentially “risking” its fiscal stability to meet the shortfall in funding.

“It’s a huge gamble; this road will bring very little, if any, benefit,” he added.

“It’s only really a relief road for some rat running and will do enormous damage to the environment in the process.

“There are still lots of hoops to jump through and opportunities for opposition to this misguided road.”

The county council said an updated report on the project would be brought to a meeting of the council’s cabinet as soon as possible, with members asked to approve submission of the planning application.