Industrial group GFG Alliance gained planning permission in January 2018 for the near-£130 million expansion of its existing aluminium smelter in Fort William.

The Keppie-designed project is ready to start with production at the plant originally expected to start next year.

However, GFG said it needed to know car manufacturers would stay in the UK after Brexit.

Jay Hambro, of the GFG Alliance, told BBC Radio’s Good Morning Scotland programme: “We’ve been working very closely with Highland Council to get planning permission for our site.

“We’ve been working very closely with lots of manufacturers of the equipment, so are ready to go but just need a moment of clarity as to the future and then will push the button.”

Just last month, an industry body warned that UK car production could be cut by more than a third if the UK withdraws from the EU without an “ambitious” trade deal.