TOKYO, Feb. 2 (Xinhua) -- Tokyo stocks closed lower Friday on increasing concerns about the ongoing rise in U.S. Treasury yields which has weighed on the market amid expectations inflationary pressures could build in the United States.

The 225-issue Nikkei Stock Average dropped 211.58 points, or 0.90 percent, from Thursday to close the day at 23,274.53.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, lost 6.24 points, or 0.33 percent, to finish at 1,864.20.

Shares traded lower from the opening, market strategists said, as a continued rise in U.S. Treasury yields weighed on the market as investors became concerned that rising borrowing costs could adversely affect U.S. corporate earnings.

Overnight, U.S. 10-year Treasury yields touched a nearly four-year high, with the BOJ's emergency bond buying operation having a negligible effect on markets here, investment analysts said.

The announcement of the BOJ's operation served to push the 10-year bond yield from its starting level of 0.095 percent to 0.085 percent.

The BOJ on Friday also increased its planned purchases of five to 10-year bonds from 410 billion yen (3.73 billion U.S. dollars) to 450 billion yen (4.10 billion U.S. dollars).

The central bank's regular market operations see the bank usually purchase bonds through auctions.

The yen dropping slightly against the U.S. dollar after the BOJ's announcement gave brief support to exporter issues, but the U.S. dollar regaining ground in later trade reversed gains, local brokers said.

Losses were trimmed, however, on expectations the central bank will purchase exchange-traded funds (ETFs), they also said.

Equity analysts here also noted that shares being deemed overvalued following recent rises contributed to declines, while a wait-and-see approach ahead of key U.S. jobs data saw some investors opting for the sidelines.

By the close of play, securities, bank and machinery-oriented issues comprised those that declined the most, and falling issues outpaced advancing ones by 1,186 to 808 on the First Section, with 70 ending the day unchanged.

On the main section on Friday, 1,702.44 million shares changed hands, dropping from Thursday's volume of 1,816.56 million shares.

The turnover on the final trading day of the week came to 3,214.9 billion yen (29.28 billion U.S. dollars).