Trump doubles planned tariffs on Canadian metal

US President Donald Trump has said he will double the tariffs he previously announced on Canadian steel and aluminium imports into the US, taking the levies to 50% in total.

In the latest twist in a deepening trade war, Trump said it was in retaliation for 25% tariffs Ontario placed on electricity it sends to northern US states.

Trump said his tariffs would go into effect on Wednesday morning, and that he would declare "a national emergency on electricity" in those states.

He said if tariffs, including those on agricultural products were not dropped, he would hike taxes on the car industry "which will, essentially, permanently shut down the automobile manufacturing business in Canada".