The long-term future of the United Kingdom's electric car industry, which has benefited from considerable Japanese investment, is facing uncertainty under new trading arrangements being proposed by the European Union, according to a body representing auto manufacturers.

Even if a trade deal is agreed to by January, Japanese companies based in Britain may face 10% tariffs on exports of electric cars into the economic bloc, according to authoritative reports of the negotiations.

Industry representatives and analysts have warned this could make the country a less attractive investment destination for Japanese firms and ensure the EU becomes the main home to the electric car industry.