The United States will raise tariffs from 10 percent to 25 percent on $200 billion worth of Chinese imports effective Friday, according to a notice posted to the Federal Register on Wednesday.

The U.S. Trade Representative's office will establish a process to seek exclusions for certain products from additional tariffs, the Federal Register notice said.

The tariff boost was revealed just as President Donald Trump announced on Twitter that Chinese officials are still coming to the U.S. to "make a deal" on trade.

Trump said in the tweet that he would be "very happy with over $100 Billion a year in Tariffs filling U.S. coffers."

His comments followed a Reuters report that quoted U.S. government and private-sector sources as saying China had backtracked on almost all aspects of a draft trade agreement with the United States.

Global equities tumbled toward five-week lows as the escalating trade fight fed worries about the world economy and investors sought the safety of bonds and the Japanese yen, which hit a six-week high against the U.S. dollar.