The prime minister misspoke when he claimed Bridgend was to be a great centre of battery manufacturing, the UK government has confirmed.
Boris Johnson has been asked to apologise for his comments in the Commons on Wednesday.
Labour’s Nia Griffith said it was “deeply unfair” when the town was “reeling from the closure of Ford”.
The UK government said it is working with investors on battery manufacturing plans across the United Kingdom.
Plaid Cymru called for a retraction for the comments, made in response to a question from Plaid’s Westminster leader Liz Saville Roberts.
No plans have been announced for a battery factory in Bridgend.
In December, it was announced that a Britishvolt electric car battery factory that would create 3,000 jobs was going to be built near Blyth, Northumberland, rather than St Athan in the Vale of Glamorgan as had been previously planned.
That announcement came days after a decision from another company, Ineos, to build its 4×4 vehicle in France rather than Bridgend – just 13 miles away from St Athan.
Britishvolt had previously signed a memorandum of understanding with the Welsh Government in July 2020 to build the plant in St Athan, Vale of Glamorgan.
Speaking at Wednesday’s Prime Minister’s Questions, Mr Johnson had said Bridgend was “going to be the one of the great centres of battery manufacturing in this country if not the world”.
A video of Mr Johnson’s comments was later tweeted by the Welsh Secretary Simon Hart.
The UK government later confirmed to BBC Wales that Mr Johnson had misspoken when he made the comments.
Speaking later, Plaid Cymru MP Liz Saville Roberts said: “Whether intentional or negligent, the Prime Minister’s answer misled the people of Wales, while the Secretary of State for Wales threw his support behind him.”
“We are inured to his abuse of facts. But for Mr Hart to broadcast false information about investment in his own country – the interests of which he has a duty to defend – is reprehensible. I expect a retraction and apology.”
Shadow Welsh Secretary Ms Griffiths said: “It is deeply unfair for the prime minister to be so loose with his words when Bridgend has faced so many set backs on his watch. The community is still reeling from the closure of Ford and the loss of the Ineos project to France.”
Peter Hughes, Unite Wales Regional Secretary said: “The Prime Minister’s comments today regarding Bridgend are news to everyone in Wales.”
A UK government spokeswoman said they would “continue to work with investors” to progress plans for UK battery manufacturing.
“We are investing heavily to expand the UK’s supply chain for cleaner vehicles, while working with our auto industry to ensure it remains competitive for years to come.
“As part of the prime minister’s Ten Point Plan, we recently announced nearly £500m funding – as part of a wider commitment of up to £1 billion – to support the electrification of vehicles and their supply chains, including developing Gigafactories across all parts of the UK.
“We will continue to work with investors to progress plans to mass manufacture the batteries needed for the next generation of electric vehicles.”