Japanese carmaker Nissan has warned that a no-deal Brexit could make its European business model unsustainable.
Nissan's European chairman, Gianluca de Ficchy, said if a 10% export tariff was introduced after the UK left the EU it would put its operations "in jeopardy".
This would be the case if the UK moved to World Trade Organization (WTO) rules after Brexit, he said.
He was speaking at Nissan's plant in Sunderland, where work on a new model of the Juke is due to start.
The Japanese firm said it had invested £100m in the plant, which also makes the Qashqai and electric Leaf models.
Mr de Ficchy said Nissan still intended to build in Sunderland, the UK's biggest car plant, but that it was difficult to plan for the future amid Brexit uncertainty.
The new Juke has been designed and manufactured in the UK, aimed specifically at European markets, with two-thirds of its components coming from the EU and 70% of production destined for the continent.
Nissan, which employs 7,000 in Sunderland, also has operations in Spain.
Mr de Ficchy said the cost of moving to WTO rules would mean the "entire business model for Nissan Europe will be in jeopardy".
The car industry is the UK's biggest exporter of goods and eight out of every 10 cars built in the UK are exported.
Speaking to the BBC, Mr de Ficchy said: "We do not know still what a no-deal means.
"There are many alternatives, and today there is a lot of uncertainty.
"The only message I can [give] is that if a no-deal will be associated with the application of 10% duties under the WTO rules, that will create an enormous problem for the overall European activities of Nissan Europe.
"If we will have to sustain 10% export duties on the vehicles that we export from UK to EU, knowing that those vehicles represent 70% of total production, the overall business model won't be sustainable.
"It's not a question of Sunderland, it's a question of the overall economic sustainability of our business [in Europe]."
He said the business was asking for tariffs not be imposed if there is a no-deal Brexit.
"We are asking not to have tariffs being applied in a no-deal scenario because otherwise the tariffs won't be sustainable for us," he said.
A spokesperson for the Department for Business, Energy and Industrial Strategy said: "We continue to work closely with the sector as they get ready for Brexit on 31 October."
