The United States has come under fire from finance ministers at a G7 meeting in Canada over its decision to impose tariffs on some metal imports.

America's closest neighbour has challenged the measures, which it describes as absurd. The EU has said the U.S. is playing a dangerous game and is taking its complaints to the World Trade Organisation.

"We know that in every relationship, in every negotiation, there are times that are more difficult," said Canadian Finance Minister Bill Morneau. "I have a strong relationship with (U.S.) Secretary Mnuchin, but I took the opportunity to express strongly our views that what they've done is not productive. We'll continue to do that.

Canada and Mexico are planning to retaliate against the U.S. measures, and the EU has already drawn up a ten-page list of tariffs on U.S. good including Harley Davidson motorcycles and peanut butter.

Donald Trump has said that the tariffs will protect steelmakers, which he claims is vital for national security. He also says that U.S. firms face barriers in Europe and other parts of the world.