Foreign Minister Katsuya Okada told his Chinese counterpart Sunday that Japan will "take action" if Beijing violates a 2008 agreement over disputed gas exploration projects.

In talks with Yang Jiechi, Okada also urged Beijing to start discussing the details of jointly developing the projects in the East China Sea, according to a Japanese diplomat who declined to be named.

"If China violates the agreement, Japan will have to take certain action," Okada said in talks on the sidelines of the Forum for East Asia-Latin America Cooperation in Tokyo.