Brexiteers condemned the 'stunt' endorsement of Theresa May's Brexit deal by Shinzo Abe tonight after Japan's PM said the 'whole world' was against no deal.
Eurosceptic Tories warned the intervention would fall flat just as Barack Obama's backing for Remain ahead of the 2016 referendum did.
Mr Abe weighed into the Brexit debate at a Downing Street press conference with Mrs May - warning the 'world is watching' and pleading with MPs to back her deal in a showdown vote on Tuesday night.
He said Japan uses Britain as a 'gateway' to the EU and warned of the impact on jobs and firms of a no deal Brexit.
In a rare boost for Mrs May, the Japanese PM hailed the progress Britain has made in securing a Brexit deal and gave his 'total support' to her deal.
He told a press conference in No10 today that the 'world is watching' as Britain exits from the European Union.
He said: 'For Japan, the UK is the gateway to the European market, Japanese businesses have created 1,000 bases in the UK offering more than 150,000 jobs.
'It is the strong will of Japan to further develop this strong partnership with the UK, to invest more into your country and to enjoy further economic growth with the UK.
'That is why we truly hope that a no-deal Brexit will be avoided, and in fact that is the whole wish of the whole world.'
Mr Abe - one of the PM's closest political allies - hailed Mrs May's hard work in securing a plan.
Japanese PM Shinzo Abe today backed Theresa May's Brexit deal - as he said the 'whole world' wants to avoid a no deal (pictured together today in Downing Street)
In a rare boost for Mrs May, the Japanese PM hailed the progress Britain has made in securing a Brexit deal and gave his 'total support' to her deal (pictured together in No10 today)
Mr Abe (pictured with Theresa May in Twickeham today) said Japan uses Britain as a 'gateway' to the EU and warned of the impact on jobs and firms of a no deal Brexit.
Shinzo Abe (pictured with Theresa May in Twickenham today) is worried about the dire impact a crash exit could have on the 1,000 Japanese companies operating in the UK
He said: 'I would like to extend my deepest respect for the strong will and hard work by Theresa for the parliamentary approval of the Withdrawal Agreement.
'Japan and the UK have been building a very strong partnership, not only in the political arena but also the economic area.
Britain to lend Japan Van Gogh's Sunflowers painting in Brexit charm offensive
Van Gogh's Sunflowers (pictured) , which dates from 1888 and is one of the most famous in the world, currently hangs in the National Gallery in London
Britain will lend Japan Van Gogh's Sunflowers as part of a Brexit charm offensive, it emerged today.
The painting, which dates from 1888 and is one of the most famous in the world, currently hangs in the National Gallery in London.
But Theresa May today announced that it will go on tour to Japan.
She made the revelation at a joint press conference with the Japanese PM at No10 today.
The gesture came as Mr Abe gave his full backing to the PM's Brexit plan.
Mrs May is an art fanatic well known for her love of modern art.
She is a big fan of the late Mexican artist Frida Kahlo and often wears a bracelet featuring the artist's self portraits.
He added: '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.'
Mr Abe is worried about the dire impact a crash exit could have on the 1,000 Japanese companies operating in the UK.
Eurosceptic ringleader Jacob Rees-Mogg told MailOnline: 'I think Prime Minister's are generally well advised to concentrate on running their own countries rather than other people's.'
MP Simon Clarke said: 'Today's stunt brings back memories of President Obama being wheeled out by David Cameron before the referendum.
'This is about how we implement a decision made by the British people and one which British MPs need to get right for the future of our country.
'That does not involve being stuck as a rule-taking hostage of the EU, no matter how convenient that might be for others.'
Michael Fabricant added: 'It is ironic that Shinzo Abe along with Australia, New Zealand and Canada who want the UK to join the Trans-Pacific Partnership ignore former Australian and New Zealand High Commissioners who have said that joining the trade agreement will difficult if not impossible if the UK were to sign up to the withdrawal agreement.
Mr Abe's support for Mrs May is a rare boost for the PM, whose Brexit plan has been met with an onslaught of attacks from Remainers and Brexiteers.
It comes amid turmoil in No10 after Tory rebels joined with Labour to inflict a humiliating defeat on the PM's Brexit plans last night.
They backed an amendment which means the PM will have to come back in just three days with her Plan B if her deal is rejected by MPs in next week's crunch vote.
Mrs May is set to suffer a massive defeat on her deal, and the change - put forward by Tory Remainer Dominic Grieve - allows MPs to give her instructions on the talks.
Mr Abe is one of the PM's closest allies and she had originally hoped to him as her secret weapon to drum up support for her deal when he visited the UK late last year.
But her hopes were scuppered when his trip was postponed and her plans were leaked to the media.
A string of major Japanese manufacturers have warned of the dangers of a no deal Brexit to their British operations.
Nissan, Toyota and Honda have said it could cost them millions in additional tariffs and disrupt the 'just-in-time' supply chains they rely on.
Many of the firms have set up home in Britain as a gateway to the EU market, and there are fears they could shift their operations to the continent if no deal is done
After talks with Mrs May at the G20 summit in Argentina last month, Mr Abe urged her to avoid no-deal and ensure 'transparency, predictability (and) legal stability in the Brexit process'.
Firms like Panasonic have announced they are moving their European HQs to the Netherlands because of Brexit.
His visit comes at a time of crisis for No10 after Mrs May suffered two devastating defeats on Brexit in just 24 hours.
Senior Tories 'open talks with Labour' over Brexit in desperate bid to find a way through total deadlock
Desperate cross-party talks are under way today as the political crisis over Brexit mounts dramatically.
Senior Tories have opened discussions with Labour amid fears that Parliament has descended into a 'Mexican stand-off' - with all sides vowing to block the others' plans.
The depth of the deadlock was underlined over the past two days with Theresa May suffering two humiliating defeats in the Commons, stepping up the timetable for her to spell out a 'Plan B' and restricting the Treasury's tax-raising powers if there is no-deal Brexit.
Speaker John Bercow also caused fury yesterday when he demonstrated he is willing to tear up the Parliamentary rulebook in order to bring the government to heel.
Mrs May has been privately meeting Leave-leaning Labour MPs in an increasingly vain attempt to boost support for her deal ahead of a crunch vote on Tuesday.
But the focus of ministers and MPs is already turning to what happens after the package has been defeated.
Tory and Labour MPs have been mobilising against no-deal Brexit. More than a dozen Conservatives have indicated they could vote no-confidence in the government to avoid the UK crashing out in March.
Sarah Wollaston this morning told the BBC she 'will resign the Conservative whip' if policy becomes to go for no deal.
Tory rebels joined with Labour last night to force the PM to come up with her Plan B in three days time if she is defeated on her Brexit plan in next Tuesday's crucial vote.
The decision by Commons Speaker John Bercow to let the vote on the amendment sparked uproar among furious MPs who said he tore up centuries-old legal rules to let the vote go ahead.
It came hot on the heels of a defeat on Tuesday, when MPs voted to curb the PM's tax raising powers if she pursues a no deal Brexit
The twin defeats seriously hamper Number Ten's ability to maneuver if Mrs May's deal is voted down.
And they lay bare her failure to be able to command a majority in the House of Commons.
Japan also used Mr Abe's visit to announce that they are scrapping a 23-year-old ban on UK beef and lamb imports.
The ban has been in place since the 'mad cow disease' crisis of 1996.
In total trade agreement worth some £200million were struck between British and Japanese businesses in the trip.
While toy shop Hamleys has announced it will open 30 new stores in Japan over the next five years.
International Trade Secretary Liam Fox said: 'The UK and Japan are among the strongest champions of free trade and an even closer relationship as we leave the European Union will help us to rally against the protectionist measures around the world that risk making us all poorer.
'That's why today we have committed to reduce global trade tensions, reform global trading rules and bring a new UK-Japan free trade agreement into force as soon as possible.
'On top of this, we have announced more than £200m worth of export and investment deals that will see Hamleys toy shop, Norton motorcycles and British farmers increasing their presence in Japan and supporting hundreds of jobs in both of our countries.'
The talks at Downing Street follow a visit by Mrs May to Tokyo and Kyoto in 2017.
For the first time, British and Japanese researchers and industry experts are set to work side-by-side on projects to tackle the major challenges identified by the UK's Industrial Strategy and Japan's Society 5.0 programme.
Shinzo Abe held talks with Dutch Prime Minister Mark Rutte (pictured together yesterday) as he embarks on a European tour
Labour's shadow international trade secretary Barry Gardiner said Mrs May could not give Japan clarity on Brexit.
He said: 'Theresa May's proposed deal would harm the foundations of our existing relationship with Japan.
'Japanese investors will understandably be seeking clarity on the terms of our future relationship with the EU, but it is a clarity that Theresa May cannot give – because the future political framework that Parliament is to vote on next week is no more than a flimsy statement of intent.'