By Eric Onstad, Hyunjoo Jin and Hongmei Li LONDON/SEOUL/SINGAPORE (Reuters) -U.S. prices of steel and aluminium spiked on Monday while shares of foreign steelmakers slumped after U.S. President Donald Trump said he would double tariffs on imports of the two metals to 50%.

President Trump would invoke other tariff authorities if his appeal of a trade court's ruling isn't successful, Commerce Secretary Lutnick said.

Trump announced at a Pennsylvania rally on Friday that he plans to double tariffs on steel imports to 50% from 25%.

CNN data reporter Harry Enten said he had some “troubling” news for President Donald Trump on Friday: The TACO trend, which has been used to taunt Trump, is gaining steam. “The top term that was Googled with ‘Donald Trump’ on Thursday was... it was ‘TACO,’” Enten said, referring to the acronym for “ Trump Always Chickens Out .”

Premiums for consumers buying aluminium on the physical market in the United States soared on Monday after U.S. President Donald Trump said he planned to increase tariffs on imported steel and aluminium to 50% from 25%.

Wells Fargo's Christopher Harvey thinks a 10% tariff could be split evenly between importers, corporations, and consumers.

Canada’s steel industry warned of “catastrophic” job losses, factory slowdowns and supply chain disruption after US President Donald Trump doubled tariffs on imports to 50 per cent.

The impact from U.S. President Donald Trump's plan to increase tariffs on steel and aluminium products is likely to be "minor" as India does not export steel to the U.S. "in a big way", federal steel minister HD Kumaraswamy said on Monday.