The visits would likely give rise to tense relations between Japan and China after China on Monday expressed strong dissatisfaction over Japan's granting of a visa to Kadeer, leader of the World Uighur Congress, who is accused by Beijing of masterminding the riots in China's Muslim-populated Xinjiang region in early July.

China's ambassador to Japan Cui Tiankao warned Monday that Kadeer's visit to Japan will spell trouble for China-Japan relations, according to Chinese media reports.

In addition, Chinese Deputy Foreign Minister Wu Dawei summoned Japan's ambassador to China, Yuji Miyamoto, to air China's strong discontent and called upon the Japanese government to prevent Kadeer from engaging in anti-Chinese separatist activities while visiting the country.

China even disrupted an overseas broadcast by the Japanese TV station NHK on Tuesday evening about Kadeer's visit.

A Japanese foreign affairs official, meanwhile, described China's strong expression of displeasure to the Japanese government as improper.

Lee, who has long maintained close ties with Japan, will visit Japan in September. The former president has visited Japan four times since he left office in 2000.

During his 2007 trip, Lee paid a visit to the Yasukuni Shrine, a controversial memorial to Japanese war dead, to pay tribute to his elder brother, who died while serving in the Imperial Japanese Navy during World War II when Taiwan was under Japanese colonial rule. The shrine in Tokyo is seen by China and other Asian countries as a symbol of Japanese militarism before and during WWII.

Last September, Lee made a trip to Okinawa Prefecture and delivered a speech there.

The Dali Lama is set to deliver a speech on Nov. 13 in Japan at the invitation of a Buddhist association in Shikoku. His last visit to Japan was last November.

A source familiar with Japanese foreign affairs said that in the eyes of China, Lee, the Dalai Lama, and Kadeer are "the top three bad guys, " who are deemed as masterminds of pro-Taiwan independence, pro-Tibet independence and pro-Xinjiang independence activities, respectively.

He said Japan should be mindful that China would seek revenge over Japan's decision to allow entry by the trio.

In addition, whether Japanese Prime Minister Taro Aso and his Cabinet will visit the Yasukuni Shrine on Aug. 15, the anniversary of Japan's defeat in WWII, will also have an impact on Sino-Japanese relations, the source added.

(By Y.L. Kao)