TOKYO, March 23 (Xinhua) -- Tokyo stocks plummeted Friday, with the benchmark Nikkei stock index tumbling more than 4 percent, as U.S. President Donald Trump's unilateral moves to impose higher tariffs on Chinese imports sparked widespread concerns.

The 225-issue Nikkei Stock Average dropped 974.13 points, or 4.51 percent, from Thursday to close the day at 20,617.86, marking its lowest closing level since Oct. 3.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, lost 62.45 points, or 3.62 percent, lower at 1,664.94.

All industry categories on the main section retreated into negative territory, with machinery, nonferrous metal and precision instrument-linked issues comprising those that declined the most.