Car giant BMW has followed plane-maker Airbus in warning about the consequences of Brexit uncertainty. BMW UK boss Ian Robertson says clarity is needed by the end of the summer. BMW makes the Mini and Rolls Royce and employs about 8,000 people in the UK.
Earlier, Airbus which employs 14.000 people in the UK, warned it would leave if the UK exits the single market and customs union with no transition deal.
The UK government says it is confident of getting a good deal for industry. The customs union brings together the EU's 28 members in a duty-free area, in which they pay the same rate of duty on non-EU goods.
Prime Minister Theresa May has ruled out staying in the customs union. The UK is due to leave the EU on 29 March 2019.
Mr Robertson said he needed to know what the government's preferred position was on customs and trade within months or his company - and the UK's - competitive position could be harmed.
If we don't get clarity in the next couple of months we have to start making those contingency plans... which means making the UK less competitive than it is in a very competitive world right now, he said.
That is a decisive issue that ultimately could damage this industry.
BMW has previously warned about the damage of Brexit uncertainty, and in May chief executive Harald Krueger said the company had to remain flexible about production facilities.
Transport Secretary Chris Grayling said any warning from any major company was taken seriously, but stressed that we genuinely expect to have a sensible partnership with the EU that was mutually beneficial.
He said there had been a large number of investment announcements in the UK over the last 18 months. But Security minister Ben Wallace stressed in a tweet the importance of UK military contracts to the plane-maker.
Shadow Brexit Secretary Sir Keir Starmer said ministers needed to listen to the concerns of businesses and get a grip on the Brexit negotiations.
Between 2012 and 2015, BMW Group invested £750m to upgrade manufacturing sites in Oxford, Hams Hall and Swindon. The company also has its Goodwood manufacturing plant in West Sussex, a UK sales and marketing subsidiary in Farnborough and a vehicle distribution centre in Thorne.