(Updates with meeting results, Japan PM comment, background in paragraphs 1-3, 5-6)
By Hyonhee Shin and Josh Smith
SEOUL, Sept 26 (Reuters) - Senior diplomats from South Korea, China and Japan agreed on Tuesday that their countries' leaders would meet at the "earliest convenient time", Seoul's foreign ministry said after a rare meeting aimed at kickstarting trilateral exchanges.
The three countries had agreed to hold a summit every year starting in 2008 to foster regional cooperation, but that initiative has been frayed by bilateral feuds and the COVID-19 pandemic. The last summit was in 2019.
Seoul's foreign ministry said in a statement that specific dates remained under discussion and that the countries' foreign ministers would meet "in a couple of months".
South Korea is this year's host for three-way meetings and has proposed a summit in late December, Japanese broadcaster TBS reported.
Japan's foreign minister, Yoko Kamikawa, said the three countries share the need to restart high-level talks, including summits, "as soon as possible".
"I believe it is very valuable to discuss the various challenges the region faces," she told a briefing in Tokyo.
The latest meeting was seen partly intended to assuage Beijing's concerns over the two U.S. allies' tightening cooperation after Seoul and Tokyo agreed this year to end legal, diplomatic and trade disputes over issues dating to Japan's 1910-45 occupation of Korea.
"We unanimously believe that carrying out cooperation is in the common interests of the three parties," Chinese foreign ministry spokesperson Wang Wenbin said on Tuesday. "We should work together to strengthen practical cooperation ... and make new contributions to regional peace, stability, and prosperity."
South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida have taken steps to mend ties and in August held a historic trilateral summit with U.S. President Joe Biden, where the three vowed to boost cooperation, including on defence and economic security.
A senior South Korean official said China has been proactive in seeking trilateral cooperation and arranging meetings since bilateral ties soured over the deployment in 2017 of a U.S. THAAD anti-missile system in South Korea.
"I'm sure there should be some discomfort on their side regarding our increasingly close trilateral security partnerships with the United States and Japan," the official said, speaking on condition of anonymity because of the sensitivity of the situation. "There seems to be a view there that they need to properly manage bilateral ties with us, as they saw how their THAAD responses backfired and fuelled anti-China sentiment to serious levels."