The British government made a promise to Nissan it has little power to keep

The UK government told Nissan it will try to secure "continued access" to European markets for the motor industry in Brexit negotiations.

The promise to ensure Nissan would face no tariffs selling its UK-made cars in Europe was made to keep the car-maker's factories in Britain, Greg Clark, the business minister, told the BBC on Sunday.

Clark said he went "all out" in a letter to Nissan, assuring the company that Britain would remain competitive after it leaves the European Union.

"Our objective would be to ensure we have continued access to the markets in Europe and vice versa without tariffs and bureaucratic impediments, and that is how we will approach those negotiations," Clark said.

On Thursday, Nissan confirmed that it will build two new models - the new Qashqai and X-Trail - at a plant in Sunderland, securing a total of around 35,000 jobs that depend on Nissan's UK manufacturing operation.

Prime Minister Theresa May's government was forced to deny it promised up-front cash to Nissan to secure the deal, and ministers have been under pressure to give more details of their assurances to the company.

The problem is that the European access that the UK car industry, along with other sectors, want, conflicts with statements already made by May and her ministers on the line Britain will take in its Brexit negotiations.

The UK has set out a tough line, rejecting the EU's freedom of movement requirements to maintain membership of the EU's single market.

European leaders, from French President Francois Hollande to German central bank chief Jens Weidmann, have made it clear that the UK can't expect to trade freely in the EU post-Brexit without allowing EU citizens to live and work in the UK unrestricted.

So the UK government is caught between breaking its promise to industry giants like Nissan, or that made to leave voters who expect a zero-tolerance stance on immigration.