Donald Trump’s chief economic adviser has said that the US pulled out of a joint communique at the G7 summit because of being “stabbed in the back” by Canadian prime minister Justin Trudeau.

The extraordinary comments by Larry Kudlow, one of a number of Trump officials to attack the conduct of the Canadian leader, underlines the deep divisions between the US and some of its most important allies – particularly over trade – that the joint statement was meant to overcome. Mr Kudlow accused Mr Trudeau of “essentially double-crossing President Trump”.

Mr Trump had arrived at the meeting of some of the most powerful nations on the planet amid a storm of his own making, having announced that stiff tariffs on steel and aluminium would be imposed on allies like Canada and the European Union despite howls of protest. The president appeared to stoke the flames of controversy by claiming that Russia should be reinstated into what was the G8, having been excluded over the annexation of Crimea in 2014.

The goal for the final statement from the summit was to calm such tensions, with nations like Germany and France particularly worried about Mr Trump’s “America First” policies on trade and climate. It called for “free, fair and mutually beneficial trade” as well as the sentiment that protectionism should be fought against.

Mr Trump had endorsed the statement before Mr Trudeau said at a news conference that Canada would “move forward with retaliatory measures” in response to the Trump administration’s tariffs, as well as rejecting a US demand for a sunset clause in the North American trade agreement, Nafta. Mr Trump tweeted in response that Mr Trudeau was “weak and dishonest”.

Having stunned the rest of the G7, Mr Trump landed in Singapore on Sunday for his historic summit with North Korean leader Kim Jong-un. However, Mr Kudlow’s comments on CNN’s State of the Union programme make clear that the fallout from the G7 meeting will not disappear quickly.

“He [Mr Trudeau] held a press conference and he said the US is insulting. He said that Canada has to stand up for itself. He says that we are the problem with tariffs. The non-factual part of this is – they have enormous tariffs,” Mr Kudlow said. “Here’s the thing… he really kind of stabbed us in the back.”

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Mr Kudlow said that the summit with Mr Kim had played into the forceful nature of Mr Trump’s response, as the president could not “show weakness” ahead of the Singapore talks.

“Potus [the president of the United States] is not going to let a Canadian prime minister push him around – push him, Potus around, on the eve of this [summit],” Mr Kudlow said. “He is not going to permit any show of weakness on the trip to negotiate with North Korea. Nor should he.”

While Mr Trudeau preferred not to answer questions about the spat when asked on Sunday morning, in the US the onslaught against the Canadian prime minister continued via Trump trade adviser Peter Navarro.

“There’s a special place in hell for any foreign leader that engages in bad faith diplomacy with President Donald J Trump and then tries to stab him in the back on the way out the door,” Mr Navarro told Fox News, saying that Mr Trudeau’s press conference was a “stunt”.

Emmanuel Macron lashes out at Donald Trump in speech ahead of G7

Both France and Germany hit back at Mr Trump, saying that they would abide by the communique from the G7 summit.

“Let’s be serious and worthy of our people. We make commitments and keep to them,” a statement from the office of France’s president Emmanuel Macron quoted by the AFP news agency said.

“International co-operation cannot be dictated by fits of anger and throwaway remarks,” it added.

German Chancellor Angela Merkel confirmed the EU will implement counter-measures against US tariffs on steel and aluminium, while voicing regret about Mr Trump's abrupt decision to withdraw support for the Group of Seven communique.

“The withdrawal, so to speak, via tweet is of course ... sobering and a bit depressing,” Ms Merkel said in an ARD television interview.

Foreign Minister Heiko Maas said Mr Trump’s was “actually not a real surprise, we have seen this with the climate agreement or the Iran deal”.

Mr Trump withdrew the United States from the worldwide pact reached in Paris in December 2015 to curb global warming, while last month he withdrew from a nuclear accord reached between world powers and Iran, claiming that it was one-sided in Tehran’s favour.

“In a matter of seconds, you can destroy trust with 280 Twitter characters,” Mr Mass said when asked about Trump’s U-turn, adding it would take much longer to rebuild lost trust.