The G7 summit has ended in acrimony, with US President Donald Trump lashing out at host Canada and retracting his endorsement of the joint statement.

He accused Canadian Prime Minister Justin Trudeau of acting "meek and mild" during meetings, only to attack the US at a news conference.

The summit, which ended on Saturday, was marred by disagreements over trade.

Mr Trudeau described as "insulting" Mr Trump's decision to invoke national security to justify tariffs.

In a news conference after the summit, he vowed to press ahead with retaliatory moves on 1 July.

"Canadians are polite and reasonable but we will also not be pushed around," he said.

Earlier, differences over the US tariffs on steel and aluminium imports had seemed to have been papered over in a joint communique which advocated a "rules-based trading system".

Tweeting en route to his next summit in Singapore, Mr Trump said he had instructed US officials "not to endorse the communique as we look at tariffs on automobiles".

He said the move was based on Mr Trudeau's "false statements at his news conference and the fact that Canada is charging massive tariffs to our US farmers, workers and companies".

He suggested Mr Trudeau was "very dishonest and weak".

Mr Trudeau's office said Prime Minister had said nothing he had not said before, both in public and in talks with Mr Trump.

Mr Trump had earlier signed the joint statement agreed by all the G7 nations despite the trade row.

He also tweeted defiantly about not allowing "other countries to impose massive tariffs and trade barriers on its farmers, workers and companies".

In the communique, the group of major industrial nations - Canada, the US, the UK, France, Italy, Japan and Germany - agreed on the need for "free, fair, and mutually beneficial trade" and the importance of fighting protectionism.

"We strive to reduce tariff barriers, non-tariff barriers and subsidies," they said.

Other agreements reached include:

Russia: A joint demand that Moscow "cease with its destabilising behaviour". The leaders called on the Kremlin to stop with its attempts to "undermine democracy" and to withdraw its support for Syrian President Bashar al-Assad
Iran: A pledge to "permanently" ensure Tehran's nuclear programme remains peaceful. The group said they were committed to ensuring Iran would "never seek, develop or acquire a nuclear weapon"
Climate: An agreement to disagree. The US refused to sign a pledge to implement the Paris climate change accord after Mr Trump announced he was pulling out of the agreement last June in the hope of a new "fair" deal

What else did Trump have to say?

President Trump earlier told reporters he had proposed the idea of a tariff-free G7 to other leaders and described his talks with them as "extremely productive".

"The United States has been taken advantage of for decades and decades," he continued, describing America as a "piggy bank that everyone keeps robbing".

President Trump said retaliation tariffs from his allies were a "mistake" and warned that if it got as far as a trade war, then the US would "win that war a thousand times out of a thousand".

He left the summit early to travel to Singapore for a landmark meeting with the North Korean leader Kim Jong-un to try to persuade him to give up the country's nuclear weapons. (BBC)

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