LONDON (Reuters) - British Prime Minister Theresa May and finance minister Philip Hammond will meet representatives from major Japanese businesses on Thursday as concerns about Brexit grow among some of the world’s biggest foreign investors.

Britain's Prime Minister Theresa May gives a speech in Manchester, February 6, 2018. REUTERS/Paul Ellis/Pool

Japanese firms have spent billions of pounds in Britain, encouraged by successive governments promising a business-friendly base from which to trade across the continent.

Carmakers Nissan 7201.T, Toyota 7203.T and Honda 7267.T began operating in Britain from as early as the 1980s and now build nearly half of all of Britain's 1.67 million cars, the vast majority of which were exported.

Thursday’s meeting comes amid intense debate inside May’s government about how closely Britain should remain aligned with the EU and its customs union after Brexit.

“The meeting will be tomorrow afternoon and the attendees will cover the most significant investors in the UK in such areas as banking, life sciences, technology and the manufacturing sector,” a spokesman at May’s Downing Street office said.

Many Japanese drug companies have made Britain their European base in recent years and are worried, like their peers, about the future of drug regulations, with any divergence with the European Union likely to pose regulatory challenges.

Banks Nomura, Daiwa Securities and Sumitomo Mitsui Financial Group have London bases but have already decided to set up operations in Europe to retain access to the single market as they await clarity on future trading arrangements.

Nomura’s Executive Chairman in Europe, the Middle East and Africa Yasuo Kashiwagi will attend the meeting, a spokesman at the bank said.

Nissan, which runs Britain’s single biggest car factory in Sunderland, northern England, will also be among the companies represented.

The company announced in 2016 that it would build two new models at the site after what a source said was a government promise of extra support in the event that Brexit hits the competitiveness of the plant.

“Nissan Europe Chairman Paul Willcox will join representatives from other Japanese companies in meeting the Prime Minister and Chancellor on Thursday to discuss our operations and investments in the UK,” the firm said in a statement.

Many businesses fear Britain could face a disorderly Brexit that would weaken the West, imperil Britain’s $2.7 trillion economy and undermine London’s position as the only financial center to rival New York.