BEIJING - Chinese Vice-President Xi Jinping on Wednesday said Japan's "purchase" of the Diaoyu Islands was a farce and urged Japan to stop any behaviors that infringe upon China's sovereignty.

"Japan should rein in its behavior and stop any words and acts that undermine China's sovereignty and territorial integrity," Xi said in a meeting with visiting US Defense Secretary Leon Panetta.

Xi's comments followed the Japanese government's announcement of its decision to "purchase" part of the Diaoyu Islands on Sept 10.

He said Japan's "purchase" openly questioned the legal effects of the Cairo Declaration and the Potsdam Proclamation and intensified the neighbors' territorial disputes.