By Jeff Mason

WASHINGTON (Reuters) - U.S. President Donald Trump has directed aides to proceed with tariffs on about another $200 billion of Chinese goods, despite Treasury Secretary Steven Mnuchin's attempts to restart trade talks with China, a source familiar with the matter said on Friday.

The timing for activating the additional tariffs was unclear.

The green light for the tariffs, first reported by Bloomberg, initially dragged U.S. stocks lower, fueled drops in the Chinese yuan in offshore trading (CNH=EBS) and gains in the dollar index (.DXY).

Trump, who had already imposed 25 percent tariffs on $50 billion of Chinese goods, said a week ago that he would be adding tariffs on another $200 billion in goods and had tariffs on another $267 billion in Chinese imports "ready to go on short notice if I want."

The Trump administration has demanded that China cut its $375 billion trade surplus with the United States, end policies aimed at acquiring U.S. technologies and intellectual property and roll back high-tech industrial subsidies.

The White House said in a statement that Trump had been clear that he and his administration would continue to take action to address China's trade practices and encouraged Beijing to address U.S. concerns.

A public comment period ended last week for the $200 billion tariff list, which included various internet technology products and other electronics, printed circuit boards, and consumer goods ranging from handbags to bicycles and furniture.

The U.S. Trade Representative's office has said it was working to revise the list based on issues raised in public hearings and written submissions. In previous rounds of anti-China tariffs, it has taken one to two weeks to make list revisions and another two to three weeks to begin collecting tariffs.

The decision comes despite a Treasury invitation earlier this week to senior Chinese officials, including Vice Premier Liu He, for more talks to try to resolve trade differences between the world's two largest economies.

China's Foreign Ministry said it welcomed the invitation, but Trump later raised questions about it, saying on Twitter that he was under no pressure to make a deal with Beijing and that the United States "will soon be taking in Billions in Tariffs & making products at home. If we meet, we meet?"

A Treasury spokesman did not immediately respond to a query on the status of the China talks invitation. A USTR spokesman did not respond to queries about the tariffs.

The duties already levied on $50 billion worth of Chinese goods followed a study on China's intellectual property practices released earlier this year.