RIO DE JANEIRO, Brazil –- South Korean President Lee Myung-bak and Australian Prime Minister Julia Gillard agreed Wednesday to work closely together to further develop a Seoul-based think tank on green growth, the presidential office said.

The two leaders met here on the sidelines of a U.N. sustainable development conference, known as the "Rio+20" summit, where Lee made a strong pitch for green growth as a solution to global challenges, such as the economic crisis, the rich-poor gap and climate change.

Green growth, one of Lee's trademark policies, calls for seeking economic growth through environment-friendly technologies and industries. Under the drive, South Korea set up the Global Green Growth Institute (GGGI) in Seoul to help develop strategies to promote the environment-friendly cause.

Australia has been an active partner in South Korea's establishment of the institute, and Lee and Gillard agreed to continue to cooperate closely to further develop the think tank, the presidential office said.

South Korea, Australia and 13 other nations were scheduled to sign a treaty later Wednesday that turns GGGI into an official international organization. The signatories must ratify the treaty for it to go into effect.

Lee and Gillard also noted that the two countries have increased cooperation in natural gas and mineral resources development, and agreed to strengthen consultations on foreign policy and defense, the presidential office said.

North Korea was also discussed, with the two leaders reaffirming the importance of the international community sending a strong, unified message to the communist nation so that the regime can "choose the right path" of improving its human rights record and the livelihoods of its people by giving up nuclear programs and opening up to the outside world. (Yonhap News)