Britain is “cautiously optimistic” of striking a Brexit deal with the European Union “but there is a lot of work to do to get there”, Foreign Secretary Jeremy Hunt has said.

Mr Hunt said he was “confident” the Prime Minister would succeed in her negotiations with the EU, adding: “British politics is littered with the graveyards of people who have predicted the demise of Theresa May and been proved wrong.”

His comments came as Mr Hunt became the first British minister to deliver a speech in Japanese while making his initial official visit to Japan since becoming Foreign Secretary.

Mr Hunt, who has been tipped by some as a possible future Conservative Party leader, held talks with Japanese Prime Minister Shinzo Abe and foreign minister Taro Kono, to discuss a range of issues including the future UK-Japan economic partnership and security on the Korean Peninsula.

Speaking about Brexit, he told the Associated Press: “I don’t think it’s brinkmanship. If we can’t come to an agreement, then the default is that we will leave the EU on the 29th of March.

“So that could happen. But I don’t think it’s in anyone’s interest for that to happen. So that’s why we are cautiously optimistic that we will get a deal but there is a lot of work to do to get there.”

Mr Hunt said Mrs May would speak for the whole country following his predecessor Boris Johnson’s public criticisms of her Chequers Brexit blueprint.

He added: “British politics is littered with the graveyards of people who have predicted the demise of Theresa May and been proved wrong. So I think she will succeed. Of course, Boris Johnson doesn’t agree with some of the policy decisions that she’s taken, but Theresa May has to speak not just for the 52% who voted for Brexit, she has to speak for 100% of the country and she has to find a way that builds bridges and unifies the country and that’s what I’m confident she will do.”

Mr Hunt, who spent over a year in the country in his 20s learning the language, put his skills to the test when he addressed representatives of exchange programmes in Tokyo, saying in Japanese: “To all Japanese people, Britain will always be your friend.”

Announcing that he hoped to “deepen a new era in UK-Japan friendly relations, he said: “I have had a great love of Japan since I was a young man. I have great admiration for Japanese politeness, perfectionism and determination.”

On North Korea, he added: “I think the lesson of the last few years is that the pressure works. The sanctions are very important. And so the UK and Japan and other countries have been working hard to enforce those sanctions and we stand ready to relax those when we see concrete evidence of a change from North Korea.”

Mr Hunt avoided a repeat of his earlier gaffe on a visit to China this year when he sought to curry favour with his hosts by telling them his wife was Chinese, only to refer to her as Japanese by mistake.