Japanese Prime Minister Shinzo Abe says the world does not want to see a disorderly Brexit and he fully supports British Prime Minister Theresa May's withdrawal deal from the EU.

Some of Japan's leading companies in Britain have warned that a no-deal Brexit could be a disaster.

"It is the strong will of Japan to further develop this strong partnership with the UK, to invest more into the country and to enjoy further economic growth with the UK," Abe said through a translator at a news conference alongside May, after meeting her in London.

"That is why we truly hope that a no-deal Brexit will be avoided and, in fact, that is the wish of the whole world."

Japanese firms have spent more than STG46 billion ($A82b) in Britain, encouraged by successive British governments since Margaret Thatcher promising them a business-friendly base from which to trade across Europe.

British MPs are expected on January 15 to vote down the deal May struck with the EU in November, making the future of Brexit deeply uncertain.

The options range from a disorderly exit from the EU to another membership referendum.

Abe has been one of the strongest international supporters of May's Brexit deal since it was struck.

"Japan is in total support of the draft withdrawal agreement worked out between the EU and Prime Minister May which provides for transition to ensure legal stability for businesses that have invested into this country," he said.

However, investors fear that if May's deal is defeated as is expected then the world's fifth-largest economy could be plunged into a chaotic no-deal exit from the world's biggest trading bloc that would severely disrupt supply chains.

Britain's business minister Greg Clark also said a no-deal Brexit would be a disaster, and partners such as Japan need assurance it will be avoided.

May told reporters the only way to avoid such a scenario was for MPs to support her deal.

Japanese car makers Nissan, Toyota and Honda build roughly half of Britain's nearly 1.7 million cars and have warned about the loss of any free and unfettered trade with the EU after Brexit.

Car makers have warned that their factories, which rely on the constant delivery of parts to enter production cycles, would be severely damaged if Britain leaves the EU without a trade deal, forcing the need for customs checks at borders.

In a sign of the concern, Honda said on Thursday it would shut its British operations for six days in April to help it counter any disruption.