"Our three countries agreed that we will not accept further nuclear tests or further provocations from North Korea," South Korean President Lee Myung-Bak said.
Lee met today with Chinese Premier Wen Jiabao and Japanese Prime Minister Yoshihiko Noda for a one-day summit.
Regarding their differences on Korean Peninsula specially over North Korea, Wen said all sides concerned should ease tensions with wisdom, patience and goodwill.
Fears of a third North Korean nuclear test have grown after a failed rocket launch by Pyongyang last month.
Wen said the three leaders gave great attention to the situation in Northeast Asia.
"Peace and stability of Northeast Asia not only involve the interests of all the nations in the region, but also work as a foremost precondition for sustainable development and prosperity there," Wen said.
China, Japan and the ROK, as major nations in Northeast Asia, have incumbent responsibility in the region, he said.
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"We should absolutely get rid of the Cold War mentality and work hard to address relative issues through dialogue and negotiations, keeping in mind the legitimate security concern of all sides," he said.
"What is the most urgent (for us) is to make all-out efforts to prevent the escalation of tensions on the Korean Peninsula," he added.
"All the sides should give full play to their wisdom, keep patient and display their goodwill to alleviate conflict, and return to the right track of dialogue and negotiations," Wen said, calling for continued efforts for denuclearisation of the Korean Peninsula through the six-party talks.
The six-party talks, which involve the North Korean, South Korea, the United States, China, Japan and Russia, were launched in 2003, but stalled in December 2008. Since the process got deadlocked after North Korea quit the talks in 2009.