The boss of Toyota has hinted the car manufacturer will keep its UK plants even if Britain votes to leave the EU.

Chief executive Akio Toyoda suggested the Japanese firm was looking to “deepen” its ties and would still be operating at its factory in Burnaston, Derbyshire, in 2090.

He told the Financial Times former staff had buried a time capsule at the assembly plant 25 years ago and he believed the firm’s workers would be there to open it.

He said: “From now on, like Japan, we may face some pretty tough times in the UK market. But we want to deepen our roots to deliver ever better cars, so when that capsule is opened after 100 years, all can see we’ve built a truly British company.”

His comments came as the debate around Britain’s membership of the EU intensified, with David Cameron insisting ministers in his government do not campaign for a “Brexit” until renegotiation talks finish.

The Prime Minister hopes to strike a deal on his demands at a crunch summit in Brussels next month which will then allow him to recommend that the UK remains within a reformed EU, but until the talks are concluded he stressed that all his ministers should follow the government line.

He also hinted an in/out referendum could take place as early as this summer.

Mr Toyoda suggested further investment by the car-maker could hinge on access to the wider EU market.

He told the paper: “In the sense that investment equals capacity then various things come into it, like the size of the market. But there are other kinds of investment: in research, in development, in people.”

The company employs around 3,400 staff in both Derbyshire and its engine plant in Deeside, north Wales.