The United States and European Union have agreed to establish a dialogue on trade within the next two weeks, amid tensions between US President Donald Trump and some of America’s closest at the G7 Summit in Canada.

Before arriving in Quebec on Friday afternoon (local time), Mr Trump launched a tirade against Canada and France in a mounting trade war over protectionist US tariffs on steel and aluminium.

In a tweet before leaving Washington, Mr Trump said he was looking forward to “straightening out” unfair trade deals and accused Canadian Prime Minister Justin Trudeau of “being so indignant”.

“Canada charges the US a 270% tariff on dairy products! They didn’t tell you that, did they? Not fair to our farmers!” Mr Trump tweeted.

Looking forward to straightening out unfair Trade Deals with the G-7 countries. If it doesn’t happen, we come out even better!

— Donald J. Trump (@realDonaldTrump) June 8, 2018

Prime Minister Trudeau is being so indignant, bringing up the relationship that the U.S. and Canada had over the many years and all sorts of other things…but he doesn’t bring up the fact that they charge us up to 300% on dairy — hurting our Farmers, killing our Agriculture!

— Donald J. Trump (@realDonaldTrump) June 7, 2018

But Mr Trump struck a more affable tone after a meeting with French President Emmanuel Macron on Friday, saying the French leader was helping to resolve trade issues.

“Something’s going to happen. I think it will be very positive,” Mr Trump said, without elaborating.

Leaders from the other Group of Seven nations Britain, Germany, France, Canada, Japan and Italy have gathered for a two day summit in the town of La Malbaie where they are expected to discuss trade, innovation and security.

In a tweet before the summit, French President Emmanuel Macron had said he expected this year’s summit would be particularly “demanding”.

“Tensions are rising everywhere,” he wrote.

European leaders gather on the first day of the G7 summit in Canada on June 8. Photo: Getty Images

Surprise comments made by Mr Trump calling for Russia to be reinstated to the G7 were expected to further isolate the US leader and heighten animosities.

“I have been Russia’s worst nightmare… but with that being said, Russia should be in this meeting,” Mr Trump said as he left the White House. “Whether you like it or not, and it may not be politically correct, but we have a world to run… They should let Russia come back in.”

Russia joined the group in the 1990s, making it the G8, but was expelled in 2014 for an armed intervention in neighbouring Ukraine.

But newly-elected Italian Prime Minister Giuseppe Conte agreed with Mr Trump on Twitter, reflecting growing disunity in the European Union.

“I agree with President @realDonaldTrump: Russia should return to the G8,” Mr Conte wrote. “It is in everyone’s interest.”

Both Mr Trudeau and Mr Macron issued thinly veiled warnings against Mr Trump this week, with Mr Macron advising the US “not to start a trade war between friends”.

Both leaders also warned that deals could be signed between the other six nations without the US.

I’ve arrived in Quebec for the #G7Summit, which brings together leaders from the world’s biggest economies. I will call on world leaders to protect the world’s oceans and ask them to prevent the vile abuse of women online. pic.twitter.com/ywiC553Y18

— Theresa May (@theresa_may) June 8, 2018

The US leader is also expected to cut short his visit in Canada to head to Singapore for a historic summit with North Korean leader Kim Jong-un on Tuesday.

It’s the first meeting between a sitting US president and North Korean leader.

Pursuing the conversation. Engaging, keeping the dialogue alive, now & ever. Sharing, reaching out, always, to promote the interests of the French people, and all those who believe in a world we can build together. With President Donald Trump, prior to the opening of G7 Summit. pic.twitter.com/SD5hzLBO0X

— Emmanuel Macron (@EmmanuelMacron) June 8, 2018

Ebony Bowden contributed reporting from New York.

– With AAP