UPDATE 4-No-deal Brexit could end Japan investment boom, envoy tells UK PM rivals

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* Japan says: "Please, no no-deal Brexit"

* Japan says some companies already moving

* Japan: Customs checks could hurt operations

* Johnson bullish on no-deal exit

* Some UK lawmakers plan to block no deal (Adds Johnson comments)

By Costas Pitas and Minwoo Park

LONDON/TOKYO, June 27 (Reuters) - Japan on Thursday cautioned the two candidates vying to replace Prime Minister Theresa May that a no-deal Brexit would be so disruptive for many companies that Japanese capital's 35-year bet on Britain could end.

In an appeal to both Boris Johnson and Jeremy Hunt, Foreign Minister Taro Kono said Tokyo did not want a no-deal Brexit, that some companies were already moving out and that more investment could go.

"I know Boris and I know Jeremy, both of them pretty well," Kono told Reuters in Osaka where a G20 summit begins on Friday.

"I have communicated with them that Japan wouldn’t want no-deal Brexit. So hopefully Brexit could be done through an ordinary and calm way."

Japan has long seen Britain as a pro-business, liberal gateway into the rest of the European Union and has around 1,000 companies based in the country, including major carmakers and technology firms. Japanese firms have invested over 60 billion pounds in Britain.

But following the 2016 vote to leave the European Union, some Japanese firms have begun moving business out of Britain, with particular concern over the impact of a possibly disorderly exit on Oct. 31.

"Please, no no-deal Brexit," Kono told the BBC. "Some companies are already starting to move their operations to other places in Europe."

Asked whether investment could leave Britain, Kono said: "It could be that there is going to be less investment."

PROROGUING PARLIAMENT ON THE TABLE

Both Johnson and Hunt have both said they would be prepared to take Britain out of the bloc without a deal, although it was not their preferred option.

No-deal means there would be no transition period so the exit would be abrupt, the nightmare scenario for many businesses and the dream of hard Brexiteers who want a decisive split.

Some pro-EU British lawmakers have said they will seek next week to block a new prime minister from taking Britain out of the bloc without a deal and against the will of parliament by trying to cut off some of the government's funding.

Johnson has been bullish, vowing that Britain would definitely leave the EU on Oct. 31, deal or no deal, although he has also said that he chances of leaving without an agreement "a million-to-one".

At a hustings with some of the Conservative Party members who will ultimately elect the replacement for May, Johnson again said he could not rule out proroguing, or suspending, parliament until the Brexit deadline to prevent lawmakers blocking a no-deal divorce.

"The way to get that deal of course is to make sure we prepare for no deal," he said, ridiculing concerns that a no-deal Brexit would hit aviation and food supplies.

"The planes will fly, there will be drinking water whatever happens on Nov. 1 in this country, and believe me there will be milk solids and glucose and whey for our Mars bars. Where there's a will, there's a way," he added.

PEUGEOT DECISION

However, car makers do not share the same optimism. French carmaker Peugeot also said on Thursday that plans to build the next generation Astra vehicle at its Ellesmere Port car plant, which would keep the site open, will depend on the terms of Brexit.

"The decision on the allocation to the Ellesmere Port plant will be conditional on the final terms of the UK’s exit from the European Union and the acceptance of the New Vehicle Agreement, which has been negotiated with the Unite trade union," it said.

The factory built around 5% of Britain's 1.5 million cars last year. The Astra will also be made at Peugeot's Russelsheim plant in Germany.

Automakers have been particularly vociferous in their opposition to a no-deal Brexit due to fears over tariffs of up to 10% on vehicles, customs delays and new bureaucracy which could cripple just-in-time production practices.

Margaret Thatcher's Conservative government had attracted Japanese carmakers to Britain in the 1980s to rebuild an ailing domestic industry with promises of access to the European single market.

Last year Nissan Motor Co Ltd, Toyota Motor Corp and Honda Motor Co Ltd made roughly half of Britain's 1.5 million cars, employing tens of thousands of people both directly and through the supply chain.

Brexiteers have long argued that the EU's biggest economy Germany, which exports hundreds of thousands of cars to Britain ever year, would not impose restrictions in order to protect that trade.

Some Brexit supporters say there would be short-term disruption but in the long term the UK would thrive if cut free from what they cast as a doomed experiment in German-dominated unity that has led to Europe falling behind China and the United States.

But Honda announced earlier this year that it will close its British plant whilst Nissan cancelled plans to build a new sports utility vehicle at its Sunderland factory in the north of England. Both blamed factors other than Brexit.

"If there's a no-deal Brexit and if they have to go through actual custom inspections physically, those operations may not be able to continue," Kono said. (Additional reporting by Michael Holden and Sudip Kar-Gupta in Paris; Writing by Guy Faulconbridge and Costas Pitas; Editing by Jon Boyle and Lisa Shumaker)