The joint exercises with coast guard and fishing vessels comes ahead of leadership change in China and Japan.
China on Friday conducted navy drills in the East China Sea amid a tense diplomatic standoff with Japan that has sparked nationwide protests and anti-Japanese riots over a disputed group of islands.
The drills come just two days after nationalistic opposition leader Shinzo Abe visited a controversial war shrine in Tokyo which honors Japan's war dead, including Class A war criminals.
The naval division of China's People's Liberation Army (PLA) held joint exercises with coastguard and fisheries vessels on Friday, official media reported.
The exercise, which involved 11 vessels and eight aircraft, was "aimed at improving coordination between the navy and administrative patrol vessels, as well as sharpening their response to emergencies in order to safeguard China's territorial sovereignty and maritime interests," Xinhua news agency quoted the PLA's Donghai fleet as saying.
"The drill included simulations of illegal entry, obstruction, harassment and intentional interference by foreign vessels when Chinese ships of the fishery administration and marine surveillance agency patrolled," it said.
China's foreign ministry kept up the rhetoric with a warning that Beijing was "unswervingly determined" to safeguard its national interests in the dispute.
Foreign ministry spokesman Hong Lei told a news conference in Beijing that escalating tensions between China and Japan were "entirely the result of Japan's illegal purchase of part of the islands."
Hong called on Tokyo to "realize and correct its mistakes," and return to negotiations to resolve the dispute over the islands, which are known in China as the Diaoyu and as the Senkaku in Japan.
Japanese foreign minister Koichiro Genba has defended the purchase of the Senkaku Islands, which sparked furious protests across China, arguing it was the result of political pragmatism.
Japan had bought the islands after the right-wing governor of Tokyo, Shintaro Ishihara, publicly announced his intention to buy them.
The uninhabited islands are claimed by both China and Taiwan, but are currently under Japan's control.
"The situation could have been much worse if Japan hadn't bought the islands," Genba added, according to a transcript of the segment aired on BBC World News.
Rising tension
Nonetheless, bilateral tensions show little signs of easing.
Xinhua called the visits by Abe and right-wing ministers and lawmakers to Tokyo's Yasukuni Shrine "an ugly show of militarism by right wingers."
"The provocative shrine-worshipping, which has already become a political routine among Japan's hardcore right wingers, should be looked at seriously," the commentary said.
Meanwhile, Beijing appeared to be cracking down hard on the nationalist movement in its own backyard, with a key "Protect the Diaoyu Islands" activist incommunicado this week, ahead of a crucial leadership meeting next month, which will decide the next generation of Chinese leaders.
Calls to the cell phone of Shenzhen-based activist Fang Xiaosong, who was the only mainland Chinese to set foot on the disputed islands during a protest action in August, went unanswered on Friday.
Fellow activist Yang Kuang, who captained the converted fishing vessel that carried the activists to the islands, where they were detained and deported by Japan, said Fang had been forced to go "on holiday" under police escort, somewhere outside Shenzhen.
"He told me ... that the state security police had visited him, disturbing his landlord and housemates, because they wanted him to leave Shenzhen," Yang said.
"But he is a small businessman ... and it could be hard for him to make a living if they insist on his leaving Shenzhen."
Yang said a number of Diaoyu activists in China were planning to set up a Shenzhen branch of the nationwide campaign group, and that Fang Xiaosong had been named as the contact person.
"The authorities have probably realized that there is about to be a large meeting [of Diaoyu activists] in Shenzhen, so they wanted to whisk him away," he said.
"The fact that one of their citizens actually set foot on the Diaoyu should bring glory to Shenzhen," Yang added.
Official Chinese media have hit out in recent days at "irrational" forms of nationalism, after thousands of people took to the streets in a wave of mass protests in Chinese cities that lasted for several weeks.
However, the government has been accused of orchestrating the protests in a number of cases.
Joseph Cheng, professor of political science at the City University in Hong Kong, said the situation appeared to have reached diplomatic stalemate and was unlikely to show much improvement as both countries prepared for possible changes of government.
"There will be a general election in Japan next year, and the leaders of both political parties are being very vocal in reiterating their stance on the Diaoyu Islands dispute," Cheng said.
"At the same time, China is about to hold its 18th Party Congress, so they can't afford to relax their stance on territorial issues, either."
Reported by Grace Kei Lai-see for RFA's Cantonese service, and by Xin Yu for the Mandarin service. Translated and written in English by Luisetta Mudie.
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