The agreement will be anounced after US Secretaries of State, Condoleezza Rice, and of Defense, Donald Rumsfeld meet their Japanese counterparts in Washington on Saturday, the daily said in its article dated in Tokyo.

"This is the first time that Japan has made its stance clear; in the past, Japan has been very indirect on the Taiwan issue," said Koh Se-kai, Taiwan's special representative to Japan. "We're relieved that Japan has become more assertive."

Japan has had formal relations with China since 1972, but not with Taiwan.

Japanese Defense Agency chief Yoshinori Ono, who was to leave Japan later Friday with Foreign Minister Nobutaka Machimura for the meetings in Washington, said the two countries would "fully discuss destabilizing factors."

Asked about China, Ono said: "Japan must have good relations. I would like to pursue common grounds" with the United States on China.

China considers Taiwan part of its territory and strongly opposes any move towards its independence. China has a considerable military force amassed on the Taiwan Strait opposite the island, which split from China in 1949.

China has threatened to use force if Taiwan ever formally declares independence and on Thursday condemned a proposed resolution in the US congress demanding resumption of diplomatic ties with the island -- Washington officially recognizes mainland China.

The agreement to be announced Sunday declaring the Taiwan Strait as a "common strategic objective" of Washington and Tokyo is the most significant alteration since 1996 of the US-Japanese Security Alliance, the daily said.

"It would be wrong for us to send a signal to China that the United States and Japan will watch and tolerate China's military invasion of Taiwan," said Shinzo Abe, the acting secretary general of the Liberal Democratic Party who is widely seen as a likely successor to Prime Minister Junichiro Koizumi.

"If the situation surrounding Japan threatens our security, Japan can provide US forces with support," he added.

"We consider China a friendly country, but it is also unpredictable," an unidentified senior Japanese government official was quoted as saying in The Washington Post.

"If it takes aggressive action, Japan cannot just stand by and watch," he added.

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