Tokyo shares ended the morning session lower as sentiment here was punched by Greece's decision to reject a bailout plan, triggering concerns over Greece's possible quit from the eurozone.

The 225-issue Nikkei Stock Average plunged 324.63 points, or 1. 58 percent, from Friday to 20,215.16.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange was down 23.43 points, or 1.42 percent, to 1, 628.66.