BEIJING, March 17 - Chinese Vice Foreign Minister Li Baodong on Monday once again asked Japan to explain its excessive stockpile of nuclear material including weapons-grade plutonium and uranium.

Japan is keeping an excessive amount of sensitive nuclear material that is beyond its actual needs, raising widespread concerns and worries, Li said at a news briefing in Beijing.

"What is Japan going to do with the material? Why does Japan need weapons-grade nuclear material?" Li said. "Japan owes the international community a clear explanation."

He also urged Japan to take substantial action to follow a peaceful path in order to eliminate the worries of the international community, especially after Japan's right-wing forces advocated revision of its pacifist constitution while denying its aggression history.

It was revealed in January that the United States offered 331 kilograms of weapons-grade plutonium to Japan during the Cold War. The highly concentrated plutonium, which is kept by Japan's atomic energy agency, could be used to produce 40 to 50 nuclear weapons. Japan holds another 44 tons of plutonium, which could be used for nuclear reactors.

The United States has been pressing Japan to return the nuclear material since the first Nuclear Security Summit (NSS) in 2010. The two sides are expected to reach an agreement at the third summit in the Netherlands later this month.

Li Baodong said on Monday Chinese President Xi Jinping will meet with his U.S. counterpart Barack Obama on the sidelines of the NSS in The Hague from March 24 to 25.