By Rupert Wingfield-Hayes
BBC News, Beijing
Mobs in China have targeted Japanese businesses in two cities to protest against Japan's attempts to gain a permanent UN Security Council seat.
Anti-Japanese feeling is relatively common in China.
In one protest, the windows of a department store were smashed.
A Japanese Foreign Ministry spokesman told the BBC that the Tokyo government was very concerned about the situation.
Anti-Japanese feeling is rife in China. Many people feel Japan has never owned up to the atrocities it committed during World War II.
China claims 35 million of its people died at the hands of the Japanese military.
In the southern city of Shenzhen, more than 3,000 protestors took to the streets on Sunday.
"Down with the Japanese empire," they shouted. "Boycott Japanese goods."
In faraway Chengdu in western China, things became violent.
Up to 10,000 protestors surrounded a Japanese department store and some began smashing its windows.
In the end, the police moved in to break the protest up.
This is not the first Chinese outburst against Japan's plans to gain a permanent seat on the UN Security Council.
Last month a private internet group began an online petition in China, opposing the move.
Already, the group claims to have gathered more than 25 million signatures.