* Japan nationalists' flotilla leaves waters near disputed isle
* More than 160 Japanese lawmakers pay respects at Yasukuni Shrine
* Tokyo, Beijing trapped in stalemate over history, territory (Adds comment from Xinhua)
By Kaori Kaneko
TOKYO, April 23 (Reuters) - Tensions flared between Japan and China and South Korea after a group of Japanese lawmakers visited a shrine seen by Asian neighbours as a symbol of Japan's past militarism and Chinese patrol vessels played cat-and-mouse with a flotilla of Japanese nationalists near disputed islands in the East China Sea.
China chastised Japan for Tuesday's visits by at least 168 lawmakers to Tokyo's Yasukuni Shrine, which honours 14 leaders convicted as war criminals by an Allied tribunal along with Japan's war dead. The mass pilgrimage came after Prime Minister Shinzo Abe made an offering and Deputy Prime Minister Taro Aso and two other ministers visited Yasukuni over the weekend.
Homage paid by leading Japanese politicians at the Tokyo shrine typically angers Japan's neighbours, who contend that it glorifies wartime atrocities.
"Tuesday's mass visit to Yasukuni ... will definitely further weigh on already strained ties between Japan and its key Asian neighbours," said China's Xinhua news agency. "Japanese politicians ... should remember that only when Japan faces up to its notorious aggressive past can it embrace a bright future."
Japan for its part protested at what it called an intrusion by eight Chinese patrol vessels into its waters near the islands, known as the Senkaku in Japan and the Diaoyu in China.
But Tokyo appeared keen to avoid a clash between the flotilla of 10 boats carrying about 80 nationalist activists and the Chinese ships. Japan's Coast Guard, which had 13 vessels shadowing the boats, urged them to leave and escorted them away.
Last year members of the same group, "Ganbare Nippon" (Stand Firm! Japan), landed on one of the disputed islets and triggered anti-Japanese protests in China, where lingering resentment over Japan's wartime aggression has been rekindled in recent days.
South Korea, where bitter memories of Japan's 1910-1945 colonisation run deep, has cancelled a trip to Japan by its foreign minister following the weekend shrine visits.
On Tuesday, a South Korean foreign ministry spokesman said matters of history should be kept separate from efforts to cooperate over unpredictable North Korea's nuclear ambitions.
"It is helpful that the region's countries and the international community work together and pool their wisdom to solve this problem (of North Korea). But when it comes to history issues like the Yasukuni visit, our government takes a firm stance. That must not be mixed," said Cho Tae-young in Seoul.
Conservatives in Japan argue they should be able to pay their respects to the nation's war dead in their own way and for many the ideological stance trumps diplomatic concerns.
"It is natural for lawmakers to worship at a shrine for people who died for the nation and every nation does this," Hidehisa Otsuji, a ruling Liberal Democrat Party (LDP) lawmaker who chairs the parliamentary group behind the visit, told a news conference. "I don't understand why we get a backlash."
Aso also shrugged off overseas rebukes. "I first visited Yasukuni on April 28, 1953 and often went there ever since," Aso, who doubles as finance minister, told reporters.
"I go there two or three times every year and it's not something that should be taken up now. There's a reaction from overseas? But that's their reaction and I don't think it will much affect Japan's diplomatic relations with other countries."
A group led by LDP Vice President Masahiko Komura has cancelled a trip to China planned for early May, but said the move was not related to the Yasukuni visits.
Abe has enjoyed sky-high popularity ratings of more than 70 percent since he took office in December and launched his "Abenomics" plan to boost growth and beat deflation with hyper-easy monetary policy, spending and structural reform.
The prime minister, who has said he regretted not visiting Yasukuni during his 2006-2007 term in office, has been walking a fine line between talking tough in the territorial row with China and leaving the door open for dialogue.
Voters want Abe to put priority on fixing the economy rather than other issues close to Abe's heart, such as revising Japan's pacifist constitution, an opinion poll showed this week.
Japanese and Chinese patrol ships have been playing a cat-and-mouse game near the Japanese-controlled East China Sea islands, where China is seeking to assert its claim to sovereignty by sending ships into the disputed waters. (Additional reporting by Kiyoshi Takenaka and Kaori Kaneko in Tokyo,Ruairidh Villar in the East China Sea and Ju-min Park in Seoul; Writing by Antoni Slodkowski and Linda Sieg; Editing by Alex Richardson)