Prime Minister Justin Trudeau has assured US President Donald Trump in a telephone call that Canada will block foreign steel and aluminum transshipments to the United States.

The prime minster, according to a Canadian readout of the conversation released on Tuesday, "raised the strong measures Canada is taking to address unfair trade in steel and aluminum."

In a separate statement, Ottawa said it was "strengthening enforcement further to stop foreign exporters from avoiding duties meant to level the playing field."

The White House confirmed Trump spoke to Trudeau but mentioned only Russia as a topic of their conversation.

"These past few days, we've looked at strengthening the measures that we already have in place because it's important that we not be taking in dumped steel from around the world," Trudeau told reporters.

"We've told the Americans that we will block the diversion (of steel). We've always had good measures in place, but if we can demonstrate that we are doing more, that's a good thing," he added.

Canada -- the top exporter of steel and aluminum to the US market -- was exempted from new US tariffs on imports of the metals unveiled earlier this month.

Since then, Trudeau has echoed Trump's message that China was flooding global markets with cheap steel. Beijing has rejected the accusation, saying it was an international problem.

Seventy-one Canadian "trade remedy measures" are already in place to prevent foreign steel from flooding into the Canadian market or using Canada as a backdoor to ship foreign steel and aluminum into the United States, said a statement.

In addition, the Canadian government unveiled on Tuesday new "anti-circumvention investigations" at the border to "identify and stop companies that try to dodge duties."

Ottawa said it would also coordinate more closely with Washington and other stakeholders to prevent the transshipment and diversion of "unfairly cheap foreign steel."