The row between China and Japan over the control of the disputed islands in the East China Sea, took a violent turn as demonstrators clashed with police as they attempted to enter the Japanese consulate in Hong Kong.
About 15 protesters burnt Japanese flags and shouted anti-Japanese slogan when police intervened to keep them away from the consulate.
"We are extremely angry. I believe all Chinese people are angry," Tsang Kin-shing one of the protesters told AFP.
A demonstration was also held outside the Japanese embassy in Beijing.
Tsang was also among the activists that landed on the islands and planted the Chinese flag - known as Senkaku in Japan and as Diaoyu in China - last month.
Meanwhile the US called for ''cooler heads to prevail'', as the situation has been dangerously heating up in the last days.
''This is the cockpit of the global economy and the stakes could not be bigger and the desire is to have all leaders to keep that squarely in mind,'' said US assistant Secretary of State Kurt Campbell, adding that Washington is not to take any side in the quarrel.
China sent two patrol ships to the archipelago after Tokyo purchased three out of the five islands from their private owners for 2.05bn yen ($26m, £16.4m).
"Japan has come up with all sorts of excuses to expand its military capabilities and repeatedly stirred up trouble on the Diaoyu issue. The Chinese government and armed forces stand firm and are unshakable in their determination to safeguard the nation's sovereignty and territory," said China Defence Ministry spokesman Geng Yansheng.
"We are watching closely the evolution of the situation and reserve the right to take reciprocal measures," he said.
The islands are located south of Okinawa and north of Taiwan and are believed to be rich in natural resources and untouched fishing areas. It is controlled by Japan but China and Taiwan also claim to the territory which lies near major shipping lanes.