The boss of Toyota's European opertions warned a no-deal Brexit could make its 海角视频 plants uncompetitive.
The Japanese car giant employs 3,000 workers at Burnaston in Derbyshire and an engine factory at Deeside in North Wales.
Dr Johan van Zyl told the BBC that no-deal would create a "very negative investment environment" in Britain and be "very, very negative" for his business.
Last ditch talks are taking place between negotiators, and Prime Minister Boris Johnson is speaking to European Commission President Ursula von der Leyen in a bid to salvage talks.
There are "significant differences" between their positions, with three critical issues that need to be resolved - fishing rights, government support for industry and how a deal is enforced.
If there was a no deal then tariffs on cross channel trade could make a big difference, said Mr van Zyl.
He added: "If 90% of what you produce in the 海角视频 is exported to the EU, and you've got to do it at a duty, then you're not competitive.
"You will not be able to compete with plants in Europe. So it is a very difficult situation
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"But let's see what the outcome of the negotiations is, then we can really decide what we're going to do."
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The company has, he said, already taken steps to mitigate the impact of a no-deal scenario - but there is a limit to what it can do.
Dr van Zyl added: "We have confidence in our colleagues in the 海角视频. They're doing an excellent job so far".