The White House has insisted a phone call between Donald Trump and Justin Trudeau was “amicable”, just hours after the US President attacked his neighbour over trade.

But a Canadian readout of the conversation struck a very different tone, hitting out at “baseless allegations” over its softwood lumber industry and vowing to “defend Canada’s interests” over the dairy industry.

The call came after Mr Trump attacked Canada’s decision to change the pricing of some milk products, which has driven down prices.

Canada's dairy sector is protected by high tariffs on imported products and controls on domestic production (Chris Helgren/Reuters)

“Canada has made business for our dairy farmers in Wisconsin and other border states very difficult,” the President wrote on Twitter. “We will not stand for this. Watch!”

His administration also moved to impose a hefty tariff on softwood lumber from the US’ neighbour, accusing the Canadians of unfairly subsidising prices as part of a trade dispute dating back to the 1980s.

“People don't realise Canada's been very tough on the United States...they've outsmarted our politicians for years,” Mr Trump said while signing an executive order on agriculture on Tuesday.

“This has been going on for a while and we're not going to put up with it.”

He vowed to put a “very big tariff on lumber” coming to the US, claiming that he “loves Canada” but adding: “People don’t realise Canada has been very rough on the United States. Everyone thinks of Canada as being wonderful.”

The White House has not yet released a readout of the phone call that took place hours later between Mr Trump and Mr Trudeau, but the Canadian Prime Minister’s office made its position clear.

In 90 seconds: Trump and Trudeau differ over border control

A statement said he and Mr Trump agreed on the importance of a “mutually beneficial” trade relationship between their nations, but added: “On the issue of softwood lumber, the Prime Minister refuted the baseless allegations by the US Department of Commerce and the decision to impose unfair duties.

“The Prime Minister stressed that the Government of Canada will vigorously defend the interests of the Canadian softwood lumber industry, as we have successfully done in all past lumber disputes with the US.”

The readout said the leaders would negotiate an agreement on the issue, as well as on dairy products – a trade the Canadian government claims “heavily favours the US”.

It said Mr Trudeau confirmed that Canada would uphold the North American Free Trade Agreement (Nafta), which gives the US duty-free access for milk protein substances, but that his country would “continue to defend its interests”.

A spokesperson for the White House, however, claimed Mr Trump and Mr Trudeau had a “a very amicable call”, without giving further details.

The Canadian Prime Minister has warned of a “thickening border” with the US as trade tensions continue to escalate.