TOKYO, April 19 (Xinhua) -- Tokyo stocks extended gains Thursday morning on the back of U.S. shares advancing overnight.

The 225-issue Nikkei Stock Average gained 137.94 points, or 0.62 percent, from Wednesday to 22,296.14.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, added 8.42 points, or 0.48 percent, at 1,758.09.

Nonferrous metal, iron and steel, and oil and coal product-linked issues comprised those that gained the most by the morning break.