Businesses and politicians have united in a bid to bring the A12 up to motorway standard between London and Ipswich.

They want the “M12” to be three lanes from the M25 at Brentwood to the A14 junction at Copdock Mill just south of Ipswich.

And the New Anglia Local Enterprise Partnership wants to see a major reconstruction of the Copdock Mill junction that causes serious problems for motorists heading in all directions.

Rodney Bass, Essex cabinet member for transport, is urging MPs to demand government in the road. He described it as “the transportation backbone of the Essex economy”.

Although his comments echo earlier calls for A12 upgrades from Witham MP Priti Patel, and demands from Chelmsford MP Simon Burns for part of the road to be made a motorway, it is the first time it has been suggested the entire section of road to Ipswich should be developed.

Mr Bass said: “What is needed is a triple lane motorway between the M25 and Ipswich – no ifs and no buts.

“This sort of scheme at an investment cost of some £2 billion and suitable investment in the A120 and A127 would do more to stimulate economic growth than wasting government money on HS2.”

Ipswich MP Ben Gummer said he would like to see the A12 become a motorway, but warned it would take a long time to achieve.

He said: “There is no doubt that the A12 needs improvements – but it is important to have one campaign at a time.

“We’ve got improvements for the A11 nearly completed. The A14 work in Cambridgeshire will start next year and we are fighting hard for rail improvements.

“Once that battle is one, then we will look at the A12 – but we could start with some improvements to its troublesome areas like the Chelmsford and Colchester by-passes and the appalling road surface at Witham.”

Chris Starkie, managing director of New Anglia LEP said: “We are supportive of plans to improve the A12 as it’s an essential artery between East Anglia and London.

“However it is important that the road is looked at in its entirety and our focus would be on improvements around Ipswich itself, especially at the Copdock interchange, and the A12 north east of Ipswich through to Lowestoft.”

Nick Burfield, policy director of the Suffolk Chamber of Commerce, said the upgrade of the A12 to motorway standard would be a long-term ambition of its members.

He said: “We do want to see major improvements to that road and the A120 from Marks Tey to Braintree to improve links between Suffolk and Stansted airport.”

And Suffolk’s cabinet member for transport Graham Newman was in full support of Mr Bass: “This is certainly something that is very important for the Ipswich area and for the port of Felixstowe,” he said.

A Highways Agency spokesman said: “The Highways Agency fully recognises the economic importance of the A12 and A120.

“We are taking a long-term approach to road investment, and are working to finalise route strategies for our entire network by next spring.

“These strategies will set out our operational and investment priorities up to March 2021.”