The row between the two countries grew worse after weekend protests in both countries where activists sought to assert their countries' sovereignty over the Japanese-controlled islands, which are also claimed by China. The islands are known in Japan as Senkaku and Diaoyu in China.
The official Chinese media carried strongly worded articles, criticizing the Japanese protesters.
In Naha, capital of Japan's Okinawa prefecture, police said Monday they were questioning 10 Japanese activists, including local assembly members, for landing without authorization on Uotsuri Island, the largest of the islets, Kyodo News reported.
The activists swam ashore Sunday, two days after Japan deported 14 Chinese they had been holding after they landed on the same Uotsuri island earlier.
The protesters in some of the Chinese cities reportedly burned Japanese flags and vandalized Japanese restaurants and vehicles.
The Chinese Foreign Ministry handed a noted to Japanese Ambassador Uichiro Niwa Sunday, protesting the Japanese activists' landing on the island and urged Japan to stop such actions "that undermine China's territorial sovereignty," Kyodo reported quoting Chinese Foreign Ministry spokesman Qin Gang.
The Japanese Embassy, in turn, said its ambassador rejected the Chinese protest, saying the islands are part of Japanese territory. The islands have assumed importance as they are seen being rich in energy and fishing resources.
China Daily newspaper, reporting the protests, quoted analysts as saying the landing by the Japanese activists came as the United States "stepped up efforts to increase its military presence in the Asia-Pacific region," warning such developments will "complicate the regional situation."
"The landing, the third of its kind by Japanese nationalists within the year, is the latest Japanese attempt to display its so-called sovereignty over the islands," China Daily said. "The disputes over the islands have been fanned after Tokyo Gov. Shintaro Ishihara initiated a plan in April to purchase the islands from their so-called Japanese owners."
Separately, Xinhua News Agency said the landing by a "pack of Japanese right-wingers" on the island was "a scheme to net political leverage."
"A quick background-check of the right-wing politicians and organizations that sponsored this provocative bid shows that their target of much-sought prize may not be the islands themselves, but rather political leverage that could put them back in the driver's seat back at home," Xinhua said.
"Moreover, widespread sorrowful sentiment among the public that Japan has been economically overtaken by China also feeds the right-wingers who advocate getting tough with China," the report by the government-run news agency said.
The Chinese demonstrations appeared to be sanctioned by police as they seem to support the Communist Party line, The New York Times reported.
The Global Times, a newspaper owned by China's People's Daily, organized a seminar Sunday on the demonstrations, where some of the participants reportedly urged more radical action, the Times said.
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