Japan’s UK ambassador fired a warning shot to Prime Minister Theresa May, saying that Japanese automakers would have to leave Great Britain if the imposed trade barriers after Brexit make their business there unprofitable.

The ambassador’s comments were regarded as an unusually blunt warning on the risks of trade barriers, Reuters reports.

“If there is no profitability of continuing operations in the UK – not Japanese only – then no private company can continue operations,” Koji Tsuruoka said when asked how real the threat was to Japanese companies of Britain not securing frictionless EU trade.

“So it is as simple as that,” he said. “This is all high stakes that all of us, I think, need to keep in mind.”

All three bosses from Nissan Europe, Honda Europe and Toyota Europe were among the executives from 19 Japanese businesses who met with UK Prime Minister Theresa May to voice their concerns over the country’s departure from the EU.

Japan, which is the world’s third largest economy, has voiced its strong concerns about the impact of Brexit on the UK, which is also the second-most important destination for Japanese investment after the United States.

“The point about frictionless trade and tariff-free trade was made in the meeting [with the Japanese businesses] and acknowledged by the government and all sides as being important but nothing firm,” said an anonymous source familiar with the discussions.