European car giant Stellantis on Tuesday warned that it could halt production in Britain should the new government fail to provide greater help with the transition to electric vehicles.

The company's brands include Chrysler, Fiat and Peugeot in addition to Vauxhall cars made in the UK, whose Conservative government has delayed by five years to 2035 a ban on the sale of new petrol and diesel vehicles.

Britain's main opposition Labour party, widely expected to win a general election on July 4, has pledged to revert to the Conservatives' original 2030 date.

Addressing an auto-sector event in London on Tuesday, Stellantis UK Group Managing Director Maria Grazia Davino said there was a lack of demand for electric vehicles in the UK.

"Fact is that demand is not there, following the expectation and the glide path designed by the government," she told a press conference hosted by UK car industry body SMMT.

"We need to support that demand growth, and we need the government also to support it."

Davino said that while Stellantis had "undertaken big investments" at its UK plants in Ellesmere Port and Luton, "if this market becomes hostile for us, then we will enter an evaluation of producing elsewhere".