Britain's Prime Minister Theresa May and Japan's Prime Minister Shinzo Abe | Kirsty Wigglesworth/AFP via Getty Images Theresa May to Japan: We’ll keep EU market access post-Brexit ‘The UK remains the best place in Europe to run and grow a business,’ the British PM said.

British Prime Minister Theresa May Friday sought to reassure Japanese investors in the U.K. that she would secure their position in the EU market through a trade deal with Brussels.

Carmakers Nissan and Toyota are among some 1,000 Japanese companies operating in Britain but both have indicated they will review future investment based on the trade deal worked out between London and the EU.

May said after talks with Japanese Prime Minister Shinzō Abe that "the U.K. remains the best place in Europe to run and grow a business."

"I have reaffirmed the U.K.'s desire for an enduring deep and special partnership with the EU, including a bold and ambitious free trade agreement," May said.

Nissan only announced it would build two new car models at a plant in Sunderland after government assurances it would remain competitive post-Brexit. Toyota committed to a £240 million investment at its plant in Derby with £21 million in government support. Both export to EU markets and employ thousands.

Japanese businesses have so far invested more than £40 billion in the U.K., May said after talks with Abe at Chequers, the Prime Minister's country retreat.

Abe is the first leader to visit Chequers during May's tenure.

Japan is also in talks with the EU about a comprehensive free trade agreement that would also cover the automotive sector. The European Commission is aiming to resolve talks by the end of the year.