(Adds comments on Japan's military policy, sex slaves)
By Jack Kim
SEOUL, July 4 (Reuters) - China and South Korea have a common interest in ensuring Tokyo is held to account for its wartime past, Chinese President Xi Jinping said on Friday, amid their shared concerns about Japan's more assertive security strategy.
Tokyo's new defensive policy, adopted in a cabinet resolution this week, has angered China, whose ties with Japan have frayed due to a maritime row, mistrust and the legacy of past Japanese military aggression.
Xi's comments, made on the second day of a visit to Seoul, were dismissed by Japan as hindering peace and cooperation in the region.
Japan took a historic step away from its post-war pacifism on Tuesday by ending a ban that has kept the military from fighting abroad since 1945, a victory for Prime Minister Shinzo Abe, but a move that has riled China.
The change, the most dramatic policy shift since Japan set up its post-war armed forces 60 years ago, will widen Japan's military options by ending the ban on exercising "collective self-defence", or aiding a friendly country under attack.
"China and South Korea have similar experience in history and shared interest on the issue of history related to Japan," Xi said, adding their two assemblies have worked effectively in seeking a sincere apology from Japan.
Xi made his comments during talks with the speaker of South Korea's parliament, as the two countries' ties with Japan are tested by what they see as Tokyo's failure to atone for its occupation of the two countries before the end of World War Two.
"In China, there is a saying, 'Past experience, if not forgotten, is a guide for the future,'" Xi said.
Xi and South Korean President Park Geun-hye share concerns about Japan's decision to lift the ban on collective slef-defence, Park's office said.
"They shared the view that the Japanese government should abandon politics that do not have enough support from its public and transparently pursue a defence and security policy that more closely adheres to its pacifist constitution."
Some voters in Japan worry about entanglement in foreign wars. Others are angry at what they see as a gutting of Article 9 by ignoring formal amendment procedures. The charter has never been revised since it was adopted after Japan's 1945 defeat.
JAPAN SAYS WAR TALK UNHELPFUL
Chinese media reported Xi proposed to hold joint anniversary events with South Korea next year to mark its victory over Japan and then-united Korea's liberation in 1945, during a summit meeting with Park on Thursday.
Park did not immediately agree to the proposal for a joint commemoration, but said South Korea planned to hold a "meaningful" event, her office said.
Japan said the drive by China and South Korea to dig up the past was not helpful to improving relations.
"Attempts to take up history in vain and make it an international issue would not contribute at all to building peace and cooperation in the region," Chief Cabinet Secretary Yoshihide Suga told a news conference.
The legacy of Japan's 1910-1945 colonial rule of the Korean peninsula has complicated ties between two strong allies of the United States in the region that are also, along with China, involved in diplomatic efforts to end North Korea's nuclear and missile programmes.
South Korea and China also have separate disputes with Japan over territorial claims.
The United States, which defeated Japan in World War Two and then became its close ally with a security cooperation treaty, welcomed the Japanese move and said it would make the U.S.-Japan alliance more effective. (Additional reporting by Kiyoshi Takenaka in Tokyo and Ben Blanchard in Beijing; Editing by Jeremy Laurence)