China Wednesday vowed a "steadfast" military defence of its territorial integrity, after a report said Japan and the United States will draft a plan to counter any Chinese invasion of disputed islands.
Japan's Nikkei newspaper, citing an unidentified US Pentagon source, said Japanese and US officials will come up with the joint military plan on retaking the outcrops in the East China Sea if China seizes them.
The joint preparations, to be finished by the summer, will be the first by the allies to address the threat of attack on a specific area held by Japan, the respected business daily said.
The report added that it was intended as a deterrent against Beijing over its claims to the Japanese-controlled islands, known as Senkaku in Japan and Diaoyu in China.
Tensions over the dispute have mounted in recent months, with Beijing repeatedly sending ships to waters around the islands to intensify its claims. Tokyo has alleged that a Chinese frigate locked its radar on a Japanese destroyer in January.
In a faxed response to AFP, China's defence ministry said it had seen the Nikkei report and reiterated Beijing's stance that the islands belong to China.
"The determination and will of Chinese military forces to safeguard China's sovereignty and territorial integrity are steadfast," the ministry said.
"We firmly oppose any action that could further complicate and magnify the situation."
The United States has repeatedly said the Japan-US defence alliance applies to the islands, meaning US troops would act with their Japanese counterparts if China physically takes them over.
General Shigeru Iwasaki, chief of staff of the Japanese Self Defense Forces Joint Staff, will meet with Admiral Samuel Locklear, commander of the US Pacific Command, in Hawaii this week to discuss the plan, the Nikkei said.
Japan and the United States already have such joint action plans to deal with possible crises in the Korean peninsula or in the Taiwan Strait, the newspaper noted.
Wednesday was a public holiday in Japan and government officials were unavailable to comment on the report.
On Sunday, China's newly installed President Xi Jinping said he would fight for a "great renaissance of the Chinese nation", in comments seen as promoting patriotism under the one-party rule of his communist regime.
Xi has close ties to China's expanding military -- the navy took delivery of its first aircraft carrier last year -- and called for the armed forces to strengthen their ability to "win battles".
Japan too has expressed a new strain of nationalistic rhetoric under its hawkish prime minister, Shinzo Abe, who Sunday called on new graduates of the National Defence Academy to guard the country against "provocations".
Also on Sunday, Abe's Liberal Democratic Party pledged at its annual convention to accelerate efforts to reform Japan's pacifist post-war constitution and create a fully fledged military.