BEIJING, Feb. 21 -- China here on Friday called on Japan to face the international community about its weapons-grade plutonium.

"China has grave concerns over Japan's storage of weapons-grade plutonium, and lodged representations to the Japanese side recently," Foreign Ministry spokeswoman Hua Chunying told a daily press briefing.

She also noted that doubts, such as the whereabouts of the plutonium, should be clarified by Japan.

Reports say that since the nuclear security summit in Washington in 2010, the U.S. government has been pressing Japan to return 331 kilograms of weapons-grade plutonium given to the country during the Cold War. The United States plans to reach an accord with Japan before the nuclear security summit in the Netherlands this March.