South Korea, China and Japan have been in talks to prepare a joint declaration that includes calls to resolve the North Korean nuclear issue, government sources said Monday.

The joint declaration would be adopted during a summit among President Park Geun-hye, Chinese Premier Li Keqiang and Japanese Prime Minister Shinzo Abe at the end of this month or the start of next month, the sources said on condition of anonymity.

The trilateral summit in South Korea will be held for the first time in more than three years, although the exact date has yet to be announced.

Aside from issues related to trilateral cooperation, the statement will include the three countries' joint position on the North Korean nuclear issue, the sources said.

It will urge Pyongyang to abide by U.N. Security Council resolutions banning the North's nuclear and missile development and a 2005 six-party deal under which it agreed to give up its nuclear weapons program.

The three leaders also plan to express their joint resolve to work together to resume multilateral talks aimed at dismantling the North's nuclear program.

North Korea has come under growing pressure from its neighbors to halt its nuclear weapons development, most recently through statements issued during summits between Park and Chinese President Xi Jinping, Xi and U.S. President Barack Obama, and Park and Obama last week.

China, North Korea's largest ally and benefactor, has increasingly voiced its opposition to North Korea's nuclear program.

The joint declaration could also call on Japan to fully acknowledge its wartime aggressions against South Korea and China, an issue that has long hampered trilateral cooperation. (Yonhap)