Peugeot-maker PSA said in 2019 it wanted to keep open its northern England Ellesmere Port plant by building the new Vauxhall/Opel Astra there, but that would depend on the outcome of Britain's departure from the European Union.

On Dec. 24, London and Brussels sealed a deal for tariff-free trade, dependent on the level of local content in goods, with rules becoming stricter on greener vehicles this decade. CEO Carlos Tavares said the company should be able to comply.

"We are now deciding where we are going to put those investments and we do not forget ... that we have a strong asset, which is a brand called Vauxhall," he said on Tuesday.

"Most probably we will be able to make a decision within a few weeks."

At his first news conference since the creation of Stellantis on Jan. 16, Tavares repeated a promise not to close factories as a result of the merger. read more

But Brexit has made carmakers weigh up whether British sites can remain viable export hubs to the European Union, should instead build models for Britain and other right-hand drive and non-EU markets, or potentially close.

Stellantis, whose brands include Peugeot, Citroen, Fiat and Vauxhall, sold around 340,000 cars in Britain in 2019 but built only 62,000 Astra cars, many of which were exported as firms tend to make a model at one or two sites for sale across Europe.

Tavares also warned on the effect of an upcoming UK ban on the sale of new combustion engine-only cars from 2030 but said the Brexit trade agreement meant it was possible to make its electric vehicle investment in either Britain or the EU.

"The biggest market is on the continental European side so if you look at it from a pure logistic perspective or from a paperwork perspective, perhaps it is better to put it in continental Europe."

"It depends also on the UK government willingness to protect some kind of automotive industry."