A ‘no deal’ Brexit would cost Honda ‘tens of millions of pounds’ and damage its competitiveness, the company has said.

But the Japanese car maker has said it would continue to use its plant in Swindon even if the UK leaves the EU without a deal.

Ian Howells, the boss of Honda in Europe, says the company’s costs could rise significantly if no free-trade deal is reached with the EU and tariffs on parts it imports from the continent are applied.

While the plant in Swindon uses hundreds of thousands of parts a day, it only keeps an hour’s worth of stock, with parts and components being delivered to the South Stratton factory on a ‘just in time’ basis.

“From an administrative point of view, we’d probably be looking at 60,000-odd additional bits of documentation we’d have to provide to get product to and from Europe,” Mr Howells told BBC Radio 5 Live.

“If we end up with WTO tariffs, we’d have something like 10 per cent of costs in addition on products shipped back into Europe and that would certainly run into tens of millions. And likewise, when we’re looking at components coming the other way, again tens of millions in tariffs potentially coming into the UK.

“That impacts our productivity, certainly in terms of the flow of product, but also it does hit potentially our competitiveness. Of course if we are shipping and competing against a European manufacturer in Europe, they’re not incurring those tariffs.”

But Mr Howells said the costs and difficulties of closing Swindon and moving production elsewhere meant it would still be easier to keep the assembly plant running.

He said: “The UK forms part of our global network of manufacturing plants, so the only place we produce the vehicle we produce at Swindon is in Swindon itself. The logistics of moving a factory the size of Swindon would be huge and as far as we’re concerned, we’re right behind supporting continued production at Swindon.”

The company has consistently told the Adver that it would prefer Britain to remain in the Customs Union after it leaves the EU.