Uncertainty over Britain's exit from the European Union halved new investment in the UK car industry as the government plans for post-Brexit trade with the EU are widely perceived to be unrealistic, the nation's largest car manufacturing lobby said Tuesday.

Public announcements of fresh investments in new plants, machinery, tooling, equipment and model development fell to 347.3 million pounds ($461.1 million, €395.5 million) between January and June 21, down from £647.4 million in the first half of 2017.

"There is growing frustration in global boardrooms at the slow pace of Brexit negotiations," said Mike Hawes, chief executive of the Society of Motor Manufacturers and Traders (SMMT).

At stake is the future of one of Britain's manufacturing success stories since the 1980s — a car industry employing over 800,000 people and generating revenues of $110 billion.

Imponderables galore

With only nine months left until the UK is due to leave the EU, little is yet clear about how businesses will develop with or without a negotiated exit deal with the world's largest trading bloc.

There is a growing sense of nervousness among business leaders about the prospect of Britain crashing out of the bloc without a proper agreement in place.

Around 52 percent of the UK's total $1.1 trillion trade in goods last year was with the EU. Theresa May wants to sign a free trade agreement and negotiate a customs arrangement to ensure as frictionless trade as possible.

SMMT chief Mike Hawes said the British government's current position — leaving the EU single market and the customs union — would severely hurt the auto industry.

hg/mm (Reuters, AFP, AP)