Kyodo News agency said the outline for potential Chinese attacks was part of a confidential report on Japan's defense strategy drawn up by military planners in September.

The report said China would "strengthen its military capability in order to demonstrate its capability to Taiwan and the United States, and will be the greatest military power in the Asia-Pacific region in the future," Kyodo said.

In the case of a clash between China and Taiwan, which Beijing regards as a renegade province, China could attack parts of Japan to prevent aid from US forces based in the country, the report said.

Under a second scenario, Beijing would try to take over disputed islands between Taiwan and Japan -- called Senkaku by Japan and Diaoyu by China -- to rally support if public criticism challenged the communist leadership.

The report also listed a third scenario in which the Defense Agency believes China could take military action to secure its interests in the East China Sea where Tokyo and Beijing dispute the development of gas fields near their maritime boundary.

A spokesman for the Defense Agency declined comment on the Kyodo report, but confirmed the agency filed a report in September on Japan's defense capability.

According to Kyodo, the defense planners called for diplomatic efforts to avoid conflicts with China.

The report said "economic and technological cooperation from neighboring countries is essential for a stable China," Kyodo said.

In a controversial report last month, an advisory panel to Prime Minister Junichiro Koizumi said Japan should study acquiring the ability to launch pre-emptive strikes on foreign missile bases.

Japan, which is closely allied with the United States, has had a pacifist constitution since World War II, with its military known as the Self-Defense Forces.