A former envoy to France has taken the rare step of urging Ambassador to China Uichiro Niwa to resign due to his vocal opposition to the Tokyo Metropolitan Government's plan to buy some of the Senkaku Islands.

"Niwa is not the right person for the job in the current climate of strained relations between Japan and China," Hiroshi Hirabayashi, vice president of the Japan Forum on International Relations, said in an editorial posted on the think tank's website in late July.

Pressure has been growing for Niwa to step down after his comments in early June about the Japan-controlled islets in the East China Sea were slammed by both ruling and opposition camp lawmakers for allegedly harming Japan's national interests. China and Taiwan claim the uninhabited islets.