The British government has said that 3,500 armed forces personnel are being kept ready to support it with its contingency plans as part of preparations for a no-deal Brexit.

The government said that it would implement plans for a no-deal Brexit in full, and begin telling businesses and citizens to prepare for the risk of leaving the EU without an agreement.

The plans also include setting aside space on ferries to ensure a regular flow of medical supplies.

With just over 100 days until Britain is due to leave the EU, Prime Minister Theresa May is yet to win the support of a deeply divided parliament for the deal she struck last month with Brussels to maintain close ties with the bloc.

Earlier, Britain's Brexit minister Stephen Barclay has said Cabinet ministers have agreed that planning for a no-deal Brexit will be an "operational priority" within the government.

Mr Barclay said the priority of the government remains securing a deal, but said no-deal planning needs to be much more of a priority for UK businesses.

"But alongside that, as part of our continuation of preparing for no deal, a responsible government needs to ensure that we are ready for that default option - which we don't want to happen - but we are ready in the event that it did happen.

"That's why at cabinet today we agreed that preparing for no deal will be an operational priority within government, but our overall priority remains to secure a deal," Mr Barclay said. 

He said the "tempo" of guidance from government to businesses and households on how to prepare for a no-deal exit from the EU would increase.

"We need to get over to business that this is something they have to prepare for", he said, with "a matter of 14 weeks until we leave the European Union."

Earlier, former Northern Ireland secretary James Brokenshire said that preparing for a no-deal Brexit was the right course of action for the UK government to take, despite the fact that it was not what it wanted to happen.

"I think it is right and proper that we maintain our work on preparing for a no-deal, however reluctantly," the Communities Secretary told BBC Radio.

"We have been taking (the prospect of) no deal seriously for quite some considerable period. It's not what we want to do, it's not what we still expect to do - because we want to see the deal secured, the vote through parliament", he said.

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Mr Brokenshire would not be drawn on whether the British cabinet would make a no-deal Brexit its "central planning assumption", stressing that "clearly it's not something the government wants to see".

He added: "There will clearly be consequences of a no deal in the short term. That's why we have been doing a lot of work in relation to, for example, the Channel ports, why we have issued 106 technical notices now, why we are recruiting another 300 people for Border Force."

Mrs May met her cabinet today with little more than 100 days to go to Brexit.

The meeting comes after the she effectively dared Labour leader Jeremy Corbyn to try to bring down her government.

Downing Street accused Mr Corbyn of a political "stunt" after he tabled a long-threatened but non-binding motion of no confidence in Mrs May, demanding she hold a meaningful vote on the Withdrawal Agreement before Christmas.

But Mr Corbyn stopped short of bringing a motion of no confidence in the government under the Fixed-Term Parliaments Act (FTPA) which, if the opposition won, could trigger a general election.

Mrs May looked likely to win a vote after Brexiteer critics in her own party and the DUP said they would back her.

But the government would also have to allow Commons time for the confidence vote to take place this week and a Downing Street source challenged Labour to strengthen its attack.

They said: "We won't allow time for what is a stunt.

"The FTPA applies if Labour wants to put down a motion under the terms of that."

Prominent Brexiteer Jacob Rees-Mogg suggested that Mrs May's position was now under threat more from pro-EU Tories than Eurosceptics if there was a full-blown confidence motion in the Government.

"Under the Fixed-Term Parliaments Act I will always support the Conservative government, I will not vote a Conservative government out of office," he told BBC Radio 4's Today programme.

Mr Rees-Mogg added: "I would have thought, actually, the Prime Minister is at greater risk in a vote of no confidence from people who see themselves as pro-EU within the party than from people who are Eurosceptic."

Mrs May had said the Commons would have the chance to debate her Withdrawal Agreement in the week MPs return to Westminster after Christmas on 7 January.

The crucial vote, which was postponed earlier this month to avoid a heavy defeat, will take place the following week.