One of the world’s largest automakers has warned that if the government does not renegotiate the Brexit deal, it may be forced to close UK plants.

Stellantis, which owns Vauxhall, Peugeot, Citroen, and Fiat, had pledged to producing electric vehicles in the United Kingdom, but this is now under threat.

It cautioned that due to restrictions governing where parts are sourced, it could incur 10% tariffs on exports to the EU.

In response, Rishi Sunak stated that he believed in Brexit.

“I voted for Brexit, and I believe in Brexit,” the prime minister told reporters on his way to Japan for the G7 Summit of world leaders.

Mr Sunak mentioned “Brexit benefits” he enacted as chancellor, as well as revisions to retained EU law that he said would save businesses a billion pounds each year.

He did not directly address Stellantis’ worries, but a spokesperson said the government was “determined” that UK vehicle manufacturing would stay competitive.

It is the first time a vehicle company has explicitly called for a rethink of the terms of the Brexit trade deal, and the BBC understands that all major UK manufacturers have expressed similar concerns to the government.

Stellantis warned that if the cost of manufacturing electric vehicles in the UK “becomes uncompetitive and unsustainable, operations will be closed.”

The automaker urged ministers to reach an agreement with the EU to retain the status quo until 2027, with a review of manufacturing arrangements in Serbia and Morocco.

Labour’s Sir Keir Starmer said the country needed “a better Brexit deal” to ensure that companies like Vauxhall could continue to operate in the UK.