Claims that a lack of improvements to the M4 in South Wales led to a decision by a British billionaire to put on hold plans for a new car plant have been dismissed as nonsense by a Welsh Government minister.

Ineos Automotive is considering scrapping its plan to build a car plant in Bridgend, where production of a new 4×4 vehicle named Grenadier was due to begin next year.

Instead the chemicals giant, which is run by billionaire Brexit supporter Sir Jim Ratcliffe, is in talks with Mercedes-Benz over acquiring the German company’s Hambach factory in Moselle, France.

Around 200 jobs were due to be created initially, but that was expected to increase to 500 once the vehicle reached full production.

The Bridgend factory was due to be built next to the huge Ford engine plant, which is closing this autumn with the loss of 1,700 jobs.

Welsh Secretary Simon Hart had told MPs the Ineos decision was linked the Welsh Government’s “inability or unwillingness” to upgrade the motorway.

But Ken Skates, the Welsh Government’s minister for economy, transport and North Wales, described that claim as “nonsense on stilts”.

“Any suggestion that the M4 decision influenced Ineos is nothing more than nonsense on stilts,” Mr Skates told the Senedd.

“The fact of the matter is the M4 decision was made in the summer of 2019 and the Ineos deal was secured in the autumn of 2019.

“In four years of negotiations with the company, on not one occasion was the M4 raised.

“It is as about credible a claim as the claim the UK Government’s failure and refusal to electrify the South Wales mainline may have influenced Ineos’s decision.

“The fact of the matter is that a site became available in France very late last week and in a very short space of time the business decided to go to France rather than remain in Wales.

“We will be seeking to recoup the £4 million that has been spent to date. There is the slightest chance it will still come to Wales but it would require the deal in France to fall through.

“We will go on working to ensure that as many job opportunities as possible come to Bridgend’s surrounding communities as possible.”

Mr Skates said he was “extremely disappointed” with the Ineos decision as the Welsh Government had invested “time, energy and money into this business”.

Former first minister Carwyn Jones, who represents Bridgend, suggested Brexit-supporting businesses had an “extra responsibility” to invest in the UK.

“Do you agree with me that those who are passionate Brexiteers should be angry at what has happened here because this undermines their passionately held belief that the UK will be better outside the EU?,” Mr Jones asked.

The minister replied: “I agree entirely with Carwyn Jones and say that this decision is somewhat perplexing given the business in question is a supporter of Brexit and there is no doubt whatsoever that Brexit is doing immense damage to the automotive industry and the economy in general.

“This disappointing news should be reflecting the poor performance of the UK Government in terms of negotiations with our European colleagues to date and should send a very real warning for the state of the automotive sector as we reach the transition period.”