The China-Japan tensions, which subsided after the recent meeting between Prime Ministers of both the countries at the Asia-Europe summit in Brussels, resurfaced after tit-for-tat public demonstrations in both the countries, asserting their respective claims over the Diaoyu islands, also called Senkaku by Japan in East China Sea.
While groups of Chinese demonstrated in several cities on Saturday asserting China's sovereignty over the islands, Chinese Foreign Ministry expressed its deep concern over Japanese "right-wing" demonstration at the Chinese Embassy in Tokyo yesterday.
Chinese Foreign Ministry spokesman Ma Zhaoxu, in a statement, said "China urges Japan to earnestly fulfill the related obligations laid out in the Vienna Convention on Diplomatic Relations and take effective measures to ensure the security of China's embassy, consulates, institutions and personnel in Japan."
Ma said China had contacted Japanese officials to "express serious concern" over the Tokyo protest, according to a separate statement.
The relations between the two nations have been strained since a collision occurred between two Japanese coast guard patrol ships and a Chinese trawler on September 7 in the East China Sea off the uninhabited Diaoyu Islands over which Japan, China and Taiwan claims sovereignty.
Japan, which control the islands, detained the skipper of the trawler for a fortnight and released him after major diplomatic fracas with China.
Subsequently, the two countries de-escalated the tensions after an informal meeting between Chinese Prime Minister Wen Jiabao and his Japanese counterpart Naoto Kan earlier this month in Brussels.
But they appeared to have resurfaced with sudden public demonstrations against each other in both the countries.
Reports from Tokyo said hundreds of people carried placards with "Japan is in danger, "Don't forgive invader China".
According to reports, two Chinese were briefly detained for protesting in Tokyo with banners, "Stop fueling harassment towards Chinese residents in Japan".
The two scuffled with Japanese nationalists and were dragged away by police officers. They were immediately released, according to police.
Chinese protesters marched in at least three cities on Saturday to vent their anger at Japan, state media and witnesses said.
The demonstrators in Xian, Chengdu, and Zhengzhou shouted slogans asserting Chinese sovereignty over the islands and calling for boycotts of Japanese goods.
More than 2,000 college students gathered in downtown Chengdu, capital of the southwestern Sichuan province, shouting aggressive slogans such as "Defend the Diaoyu Islands," "Fight Japan".
The procession marched through some of the city's main streets, with some protesters distributing Chinese national flags, official Chinese news agency Xinhua reported last night.
The protest ended at about 3.30 p.m. without any reports of violence. In Xi'an, capital of northwest China's Shaanxi province, more than 7,000 students marched onto to the streets, holding flags, banners and shouting slogans such as "Diaoyudao is China's" and "Boycott Japanese goods."
The protesters sang the Chinese national anthem while marching peacefully. Some set fire to Japanese national flags.
Riot police prevented demonstrators from breaking into a Japanese Mizuno sportswear shop, prompting Japanese shops along the route to shut down.
In Zhengzhou, capital of central China's Henan province, youths thronged to a downtown square and then marched through the city, shouting slogans "Long live the motherland," "Return the Diaoyu Islands to China."