UPDATE 1-Trump says U.S. will be 'taxing' China until trade deal is reached

(Adds additional Trump comments, background)

WASHINGTON, Aug 1 (Reuters) - President Donald Trump said on Thursday Chinese President Xi Jinping was not moving fast enough on reaching a trade agreement and that the United States would be "taxing" China until a deal is secured.

Trump, speaking to reporters, also said he was not concerned about a sharp drop in the Dow Jones Industrial Average after he announced earlier on Thursday that the United States would slap additional tariffs on Chinese goods.

The Dow closed down 285 points, reversing gains after Trump tweeted that he would impose 10% tariffs on an additional $300 billion of Chinese imports on Sept. 1.

Trump, who often says the tariffs are a tax paid by China, told reporters the proposed tariffs could be increased in stages and said they could rise above 25%.

Trump's announcement came after U.S. and Chinese negotiators wrapped a two-day meeting in Shanghai on Wednesday without significant signs of progress in resolving a trade war between the world's two largest economies.

(Reporting by Alexandra Alper; writing by Eric Beech; Editing by Mohammad Zargham and Susan Thomas)