The British government is to spend an extra £2.1 billion on preparations for a no-deal Brexit.

In his first major policy announcement, new Chancellor Sajid Javid doubled spending this year to ensure the UK is ready to leave the European Union with or without an agreement on 31 October.

The extra money will fund a nationwide advertising campaign, help Britons living abroad, ensure the supply of medicine, and improve infrastructure around ports.

It includes £1.1bn for departments and the devolved administrations to spend immediately, with a further £1bn in reserve.

"With 92 days until the UK leaves the European Union it's vital that we intensify our planning to ensure we are ready," Mr Javid said.

"We want to get a good deal that abolishes the anti-democratic backstop. But if we can't get a good deal, we'll have to leave without one."

The British government has in total allocated £6.3bn to prepare for a no-deal exit, including £4.2bn of funding for this financial year.

Mr Javid’s predecessor as finance minister, Philip Hammond, who opposed leaving the EU without an agreement, was accused by Brexit supporters of failing to spend enough money to prepare for no-deal, undermining the UK's negotiating position with Brussels.

British Prime Minister Boris Johnson has ordered planning for a no-deal Brexit to be stepped up, even though he has claimed the odds of it happening are a "million to one against".

Mr Johnson has sent his top Europe adviser David Frost to Brussels to deliver his message that the UK will be leaving on 31 October "whatever the circumstances".