China's foreign minister Yang Jiechi sparked angry exchanges with Japanese diplomats at the United Nations by accusing Japan of stealing disputed islands.
Chinese and Japanese envoys staged a series of attacks during Thursday's session after Yang heightened tensions over the East China Sea islands.
The Japanese government's purchase of the uninhabited islands from a private owner this month has infuriated Beijing and set off violent protests in several Chinese cities.
"The moves taken by Japan are totally illegal and invalid. They can in no way change the historical fact that Japan stole Diaoyu and its affiliated islands from China," said the Chinese minister.
Insisting that Japan legally incorporated the islands into its territory in 1895, Japan's deputy UN ambassador Kazuo Kodama said that "an assertion that Japan took the islands from China cannot logically stand."
Meanwhile, the Chinese embassy in Tokyo received a bullet in the post Friday, with the sender giving their name as the Japanese prime minister. A spokeswoman at the prime minister's office said only that the premier had not sent the bullet, without elaborating on any action it might take.