TOKYO, Feb. 2 (Xinhua) -- Tokyo stocks extended losses Friday morning on concern about the ongoing rise of U.S. Treasury yields further weighing on markets here amid expectations that inflationary pressures are building in the United States.

The 225-issue Nikkei Stock Average dropped 304.77 points, or 1.30 percent, from Thursday to 23,181.34.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, lost 16.01 points, or 0.86 percent, to 1,854.43.

Securities, mining and machinery-linked issues comprised those that declined the most by the morning break.