#TrumpTariffs WASHINGTON, May 30 (Reuters) - U.S. President Donald Trump on Friday accused China of violating a bilateral deal to roll back tariffs and announced a doubling of worldwide steel and aluminum tariffs to 50%, once again rattling international trade.

Trump said China had violated an agreement with the U.S. to mutually roll back tariffs and trade restrictions for critical minerals and issued a new veiled threat to get tougher with Beijing.

China, perhaps not surprisingly to some, HAS TOTALLY VIOLATED ITS AGREEMENT WITH US. So much for being Mr. NICE GUY!," Trump said in a post on his Truth Social platform.

Later, at a rally in Pennsylvania promoting an impending "partnership" between Japan's Nippon Steel (5401.T), opens new tab and U.S. Steel (X.N), opens new tab, he announced the U.S. would double steel tariffs from 25% to 50%, effective next week, which he said "will even further secure the steel industry in the United States."

He subsequently announced in a Truth Social post that aluminum tariffs would also double to 50% on Wednesday.

While China is the world's largest steel producer and exporter, very little is sent to the United States, as a 25% tariff imposed in 2018 shut most Chinese steel out of the market. China ranks third among aluminum suppliers.

On overall trade with China, Trump said he made a "fast deal" in mid-May with Chinese officials for both countries to back away from triple-digit tariffs for 90 days. He said he did this to save China from a "devastating" situation, factory closings and civil unrest caused by his tariffs of up to 145T% on Chinese rimports. Tump did not specify how China had violated the agreement made in Geneva, Switzerland, or what action he would take against Beijing.

Asked later on Friday in the Oval Office about the China deal, Trump said: "I'm sure that I'll speak to President Xi, and hopefully we'll work that out.