HONDA and other Japanese firms will pull out of Britain if the Government fails to secure free access to the EU market, according to the country’s ambassador.

The car giant, which has a manufacturing plant in South Marston, was among firms that sent top executives to discuss Brexit at a Downing Street meeting.

The ambassador’s comments raised the prospect of thousands of jobs being lost if the Government fails to negotiate a frictionless trade deal.

Koji Tsuruoka was asked after Thursday’s meeting if companies would leave Britain if there was no agreement. He replied: "If there is no profitability of continuing operations in the UK - not Japanese only - then no private company can continue operations.

“It is as simple as that. This is all high stakes that all of us, I think, need to keep in mind."

Mr Tsuruoka said manufactures in particular “expected” free access to the EU market.

Nissan and Toyota also sent executives to the meeting, along with Japanese banks Nomura, Mizuho and Sumitomo Mitsui, train manufacturer Hitachi and tech and energy firms.

They were hosted by Theresa May and cabinet ministers including Chancellor Philip Hammond, Business Secretary Greg Clarke and International Trade Secretary Liam Fox.

The ambassador spoke outside No10 afterwards.

Len McCluskey, the head of Unite, which represents Honda workers, took aim at the Government over the pace of Brexit negotiations.

Mr McCluskey said: "This continued confusion is causing damaging uncertainty among the major manufacturers that I am meeting.

“Investment decisions vital for our future are being delayed, threatening jobs."

Matt Griffith, policy director of Business West, a not-for-profit company supporting businesses in the region, warned that the ambassador’s words carried weight in Swindon and Wiltshire.

He said: “Japanese firms are highly productive – they also have a significant footprint. Not least Honda, which has its sole EU car manufacturing plant in Swindon, employing 4,000 people in skilled manufacturing jobs.

“Honda are deeply integrated into the European market. It is their largest sales market. Their supply chain is based in 15 EU countries. An unbelievable two million components flow between the EU and Swindon every day. Leaving the single market and the customs union threatens this.”

The ambassador’s comments follow Honda saying in late 2016 that it would continue to produce vehicles in Britain despite the Brexit vote.

A spokesman for automaker said: “We were pleased to be invited by the Prime Minister to share our views, along with counterparts from a range of Japanese businesses, on encouraging inward investment to the UK. The meeting provided us with an opportunity to highlight Japanese investors’ priorities as the UK leaves the EU.”

No10 insisted that the ‘roundtable’ summit had focused on how to make the UK “an even more attractive destination” for Japanese businesses.

A spokesman said: "The Prime Minister reaffirmed the Government's commitment to securing a new deep and special partnership with the EU as the UK leaves the EU."