FACTBOX-Japan, China, South Korea: trilateral ties, tensions

May 19 (Reuters) - Japan's Prime Minister Naoto Kan, South Korea's President Lee Myung-bak and Chinese Premier Wen Jiabao meet for a summit this weekend in Tokyo to show unity as Japan tries to rebuild after a massive earthquake and tsunami in March.[ID:nL4E7GG0CH]

Despite fast-growing economic interdependence, the three major Asian economies have been unable to forge an alliance that reflects their financial strength and strategic importance, with relations frayed by bilateral feuds.

Here is an overview of their tangled relations.

* TERRITORIAL SPATS:

-- JAPAN/CHINA: Ties deteriorated sharply last September when Japan detained a Chinese skipper whose trawler collided with Japanese patrol boats near a chain of disputed islands in the East China Sea, called Senkaku in Japan, Diaoyu in China.

The two sides have also been at odds over China's search for natural gas and oil in the area, where sovereignty is contested. They agreed in 2008 on principles to resolve the feud by jointly developing gas fields, but efforts have foundered since then and Japan has accused China of drilling for gas in violation of the agreement.

-- JAPAN/SOUTH KOREA: The two have a long-simmering feud over a set of desolate islands located about the same distance from both countries, called Dokdo in Korean and Takeshima in Japanese. South Korean sympathy for Japan after the earthquake turned to anger when a Japanese education panel authorised the publication of school textbooks that assert Japan's claim to the islands.

* DIPLOMATIC TIES:

-- CHINA/JAPAN: Japan invaded and occupied parts of China from 1931 to 1945 and bitterness over Japan's wartime atrocities still underpins widespread Chinese distrust of Japan.

China has criticised past high-profile visits by Japanese leaders to Tokyo's Yasukuni shrine for war dead, where among those honoured are war criminals convicted by an Allied tribunal after World War Two. No leader has visted the shrine in recent years.

China has been Japan's biggest trade partner since 2009 and both sides have tried to nurture a strategic, mutually beneficial relationship to reflect the deepening business ties.

-- Friction remains over Japan's bid for a permanent seat on the United Nations Security Council, and Tokyo's misgivings about China's economic clout and military growth.

-- JAPAN/SOUTH KOREA: Ties between the two states have been plagued for decades by problems stemming from Japan's 1910-1945 colonial rule over the Korean peninsula.

-- South Korean leaders have often criticised Japan for not being sufficiently contrite for the often-brutal colonisation and abuses such as forcing Korean and other mostly Asian women to work in brothels for Japanese troops during World War Two.

-- Japan says it has fulfilled all its legal responsibilities for the colonial period and paid proper compensation.

-- CHINA/SOUTH KOREA: Once warm ties between China and South Korea cooled after China, North Korea's main diplomatic and economic backer, refused to take a harder line toward Pyongyang, which has been blamed for two deadly attacks on the South last year.

-- China is also wary about Seoul's ties with the United States, especially after joint U.S.-South Korean military exercises in the Yellow Sea late last year following Pyongyang's shelling of the Yeonpyeong island in November.

* GLOBAL ECONOMIC RANKINGS:

China surpassed Japan as the world's second-biggest economy last year, behind the United States which is the world's largest. South Korea is Asia's fourth-biggest economy.

Source: Reuters (Compiled by Chisa Fujioka, Sui-Lee Wee; Editing by Sanjeev Miglani)