BRITAIN cannot remain in the European customs union after Brexit if it wants to strike free trade deals with other countries around the world, Theresa May has made clear.

As UK Government ministers come under renewed pressure from business leaders to ensure that they can continue to enjoy free access to EU markets once the UK has left the Brussels bloc, the Prime Minister said that she wanted to ensure that the country continued to enjoy a good trading relationship with the EU.

She stressed Britain could not be a member of "every part of the customs union" and make its own trade arrangements with other countries outside the EU.

"What we will be discussing as part of our negotiations for the future arrangements is we do want to ensure that we can trade around the rest of the world," she told Sky News.

"That means we can't be members of every part of the customs union.

"But we want to continue to have tariff-free and as frictionless trade across borders as possible because we want to ensure that we have that good trading relationship with the EU."

Her comments come 24 hours after Michel Barnier, the EU’s chief negotiator, said having frictionless trade outside the single market and customs union was impossible.

They also follow a speech on Thursday by Carolyn Fairbairn, the CBI director general, who called for the UK to remain a member of the single market and the customs union until a free trade deal with the remaining 27 member states is finalised. This, in theory, could take two years or more.

Today, David Davis, the Brexit secretary, is holding talks with senior business figures at Chevening House in Kent, the grace-and-favour country residence he shares with Boris Johnson and Liam Fox, the foreign and trade secretaries respectively.

The talks were taking place amid mounting frustration among firms at the failure so far of ministers to spell out what arrangements will be put in place if there is no trade deal with the remaining 27 by the expected date of Britain's withdrawal in March 2019.

In her speech, Ms Fairbairn said it was "impossible" to imagine a deal could be finalised that quickly and called for Britain to remain in the single market and the customs union until there was a trade agreement.

Such a "common sense" approach would, she said, avoid a "cliff-edge" break, with exporters suddenly faced with new tariffs and customs checks, and give firms the stability to carry on investing in the UK after Brexit.

"This would create a bridge to the new trading arrangement that, for businesses, feels like the road they are on," she said.

The Department for Exiting the EU has declined to give details of the Chevening talks, insisting that it was a private meeting but the guest-list is thought to include Carolyn McCall of Easyjet, Dave Lewis of Tesco and Gavin Patterson, the chief executive of BT.

Business leaders have been encouraged by the renewed willingness of ministers to engage with them, having felt shut out by the Government since Theresa May became Prime Minister last year.

At Westminster, the meeting is being seen as further evidence of Mrs May's weakness following her General Election humiliation which saw her Commons majority wiped out.