The International Monetary Fund (IMF) has joined criticism of Donald Trump’s plan to impose a 25% tariff on steel imports and 10% on aluminium.
The body warned that such a move would hurt the US as well as other countries.
It said others could follow the US president’s precedent by claiming tough trade restrictions were needed to defend national security.
Canada, the largest supplier of steel to the US, said tariffs would cause disruption on both sides of the border.
It is one of several countries that have said they will consider retaliatory steps if the president presses ahead with his plan next week.