Beijing (CNN) -- Beijing urged Japan Saturday not to "undermine China's territorial sovereignty," ahead of a planned trip by Japanese lawmakers to a disputed island chain in the East China Sea, state media reported.
Chinese Foreign Ministry spokesman Qin Gang called on Japan to immediately halt the action by some lawmakers and members of right-wing groups, China's Xinhua state news agency said.
Any unilateral action taken by Japan with regards to the island chain is illegal and invalid, Qin said, according to the news agency.
China's protest comes a day after Japan deported 14 Chinese nationals who were arrested in the area after some of the group landed on the uninhabited islands Wednesday.
The deportation was a resolution aimed at ending a diplomatic incident between the two nations, Japan's Chief Cabinet Secretary Osamu Fujimura said Friday.
Both countries claim sovereignty over the uninhabited islands, which China calls Diaoyu and Japan calls Senkaku. Ownership of the islands would give either nation exclusive oil, mineral and fishing rights in surrounding waters.
The latest incident has heightened tensions between the two nations.
The arrests of the Chinese nationals have led to anti-Japanese protests in Shanghai, Hong Kong and Beijing.
Meanwhile, the Japanese contingent intend to visit the waters of the island chain to pay tribute to World War II dead Saturday evening, Xinhua said, in another move likely to strain relations.
The Wednesday incident coincided with the 67th anniversary of Japan's official World War II surrender. On the same day, two Japanese Cabinet ministers visited the controversial Yasukuni shrine in Tokyo, which honors Japan's war dead as well as war criminals.
China and South Korea, given their respective wartime occupation and colonization by Japan, have condemned such visits.
A commentary published by the Japan Times on Friday cited diplomatic experts in Japan as saying both nations would benefit from resolving the dispute quickly, with China facing a leadership change later in the year and Japan facing separate territorial fights with Seoul and Moscow.
Adding to the regional tensions before the anniversary was South Korean President Lee Myung-bak's visit Tuesday to what the country calls Dokdo, a small group of islets that Japan claims as Takeshima.
The move prompted Japan to recall its ambassador to Seoul and warn South Korea that it will take the issue to the International Court of Justice -- a proposal rejected by Seoul. Japan's finance minister has also said he will cancel a trip to South Korea because of the dispute.
Japan has long claimed the islets as its territory, but Seoul said all Korean territory was returned after the country won independence from colonial rule by Japan in 1945.
CNN's Elizabeth Yuan and Ben Brumfield contributed to this report.