Japanese and South Korean lawmakers agreed Monday that multilateral cooperation is vital to resolve North Korea's nuclear crisis and maintain peace on the Korean Peninsula.

Close cooperation among Japan, the United States and South Korea is necessary to resolve the nuclear issue, and Russia and China should also play important roles, according to a joint declaration announced by both ruling and opposition lawmakers from both countries.

"A multilateral cooperation system should be set up to provide aid and development plans to North Korea from the international community in addition to resolving the nuclear crisis," the declaration says.