Nissan and Toyota, which both have factories in Britain, have both stressed their preference for the UK to stay in the EU after the Government called a referendum to decide the issue.
Nissan employes 8,000 people in the UK across its manufacturing, engineering and design facilities, and a further 32,000 indirectly through dealerships and its supply chain.
It said that while the EU issue was ultimately a matter for the British people to decide, the company said it believed it made the most sense for jobs, trade and costs for the UK to stay within Europe.
While the company will not be pro-actively supporting any political campaign in the run-up to the EU referendum, Nissan chairman and CEO Carlos Ghosn said: "We are a global business with a strong presence in Europe.
"We have a rich heritage in the UK with 30 years of manufacturing and engineering presence, and remain committed to building and engineering cars in the country.
"Last year we produced more than 475,000 vehicles in the UK – 80% of which are exported.
"Our preference as a business is, of course, that the UK stays within Europe - it makes the most sense for jobs, trade and costs.
"For us, a position of stability is more positive than a collection of unknowns. However, this is ultimately a matter for the British people to decide.
"While we remain committed to our existing investment decisions, we will not speculate on the outcome nor what would happen in either scenario."
He added: "We obviously want the Nissan UK plant and engineering centre to remain as competitive as possible when compared with other global entities, and each future investment opportunity will be taken on a case-by-case basis, just as it is now."
In a statement, Toyota said in 1992 it chose the UK for its first major manufacturing operations in Europe because of the open and free access to the European market, the availability of a skilled workforce, and the presence of a strong network of suppliers.
"Today, we are very pleased with the performance and competitiveness of our UK operations, which are wholly integrated into our European business," it said.
"We support thousands of jobs in our manufacturing operations and more widely in our supply chain and distribution network.
"We manufacture vehicles, engines and parts and nearly 90% of our UK-built vehicles are exported."
Johan van Zyl, president and CEO of Toyota Motor Europe, added: “We respect that the UK’s future relationship with the European Union is a matter for the British people to decide, and it is not our intention to participate in the campaign.
“We have carefully considered the implications for our manufacturing operations, should the UK leave the European Union.
"We are committed to our people and investments, so we are concerned that leaving would create additional business challenges.
"As a result we believe continued British membership of the EU is best for our operations and their long-term competitiveness.”
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