U.S. President Donald Trump's planned tariffs on all steel and aluminum imports will add to previously announced large duties on Canada and Mexico, a White House official said.

Earlier in February, Trump announced broad-based tariffs of 25 percent on Canadian and Mexican goods and a lower rate of 10 percent on Canadian energy imports.

Shortly after he made that announcement, he suspended the general duties on the United States' immediate neighbors for a month as both countries vowed to step up measures against illegal immigration and fentanyl smuggling, AFP reported.

If reimposed at the end of the 30-day period, those duties on Canadian and Mexican steel and aluminum could reach 50 percent, the official said, speaking on condition of anonymity.

Canadian Prime Minister Justin Trudeau and the Mexican president reached agreements on the postponement after talks with Trump just hours before the U.S. tariffs are set to take effect.

But as negotiations between the North American trading partners continued, Trump signed separate orders to impose 25 percent tariffs on steel and aluminum imports starting March 12, expanding the trade war despite warnings from other countries.

Canada and the European Union have since vowed to stand firm against the US president's latest swipe at steel and aluminum. | BGNES