LONDON - British Foreign Secretary Boris Johnson risked a fresh Brexit row on Friday after being secretly recorded predicting a "meltdown" in the negotiations, accusing some in the government of blocking the process and implying US President Donald Trump might handle it better.

In the latest indiscreet remarks from Britain's free-wheeling top diplomat, he also revealed talks with the United States over North Korea and plans to counter Russian aggression, and mused about relations with China.

Prime Minister Theresa May's spokeswoman refused to comment on the remarks, revealed by BuzzFeed News, but insisted she still had confidence in her foreign minister.

Addressing Conservative activists this week, Johnson said the government was reaching a phase in negotiations "where we are much more combative with Brussels".

"You've got to face the fact there may now be a meltdown," he said, ahead of a key EU summit at the end of June.

He added, according to further quotes revealed in The Times: "Take the fight to the enemy -- absolutely right. We need to -- and we will."

Johnson revealed he was "increasingly admiring" of the US president, adding: "Imagine Trump doing Brexit.

"He'd go in bloody hard... There'd be all sorts of breakdowns, all sorts of chaos. Everyone would think he'd gone mad.

"But actually you might get somewhere. It's a very, very good thought."

At a time when eurosceptics are becoming increasingly uncomfortable with moves to stay closely aligned with Brussels, Johnson said there was a risk that Britain's withdrawal "will not be the one we want".

He accused the establishment -- in particular the Treasury, led by Finance Minister Philip Hammond -- of seeking to ensure that Brexit "does as little change as possible".

As a result, Britain risked remaining "locked in orbit around the EU, in the customs union, and to a large extent still in the single market".

In a veiled criticism of May's approach, Johnson said: "Unless you have the guts to go for the independent (trade) policy, you're never going to get the economic benefits of Brexit."

 - China could 'stiff us' -

May's spokeswoman conceded there was "rigorous debate" about Brexit, adding: "The PM believes that her cabinet and her government are working hard to deliver on the will of the people."

However, she slapped down Johnson's suggestion that the Irish border issue, which has been holding up the negotiations, had been overstated.

"It's so small and there are so few firms that actually use that border regularly, it's just beyond belief that we're allowing the tail to wag the dog in this way," Johnson said.

May's spokeswoman said avoiding checks between Northern Ireland and EU member Ireland "has been a priority for the PM from day one".

"The PM is committed to the union (of the United Kingdom) and the emergence of a hard (Irish) border would put that at risk," she said.

In Brussels, the EU's chief negotiator on Brexit, Michel Barnier, said Johnson's contributions were "always very stimulating".

After accusations from other British eurosceptics that the EU side was being too tough, the Frenchman said he would not be "intimidated by this form of blame game".

Away from domestic politics, Johnson suggested May would put forward a new plan at the G7 summit in Canada for a "rapid response unit" to deal with Russian aggression, including cyber-warfare.

He revealed that US Secretary of State Mike Pompeo had asked Britain to use its nuclear expertise in helping North Korea dismantle its arsenal.

On China, he said: "We need to engage with China diplomatically, treat China as our friend and our partner, but also recognise that they are our commercial rivals. And they will try to stiff us."

A source close to Johnson said he was speaking at a private dinner "so it is sad and very disappointing that it has been covertly recorded and distributed to the media".