Environment ministers from Japan, China and South Korea have urged the United States to stay within the framework of the 1997 Kyoto Protocol and strive to ratify the pact on curbing global warming.

In a joint communique issued Sunday after their two-day meeting in Tokyo, the ministers said they "sincerely hope that the U.S. government will actively work with all the parties" for a successful outcome to the U.N. climate-change conference and the implementation of the Kyoto accord.

The statement by Environment Minister Yoriko Kawaguchi, China's State Environmental Protection Administration Minister Xie Zhenhua and South Korean Environment Minister Kim Myung Ja follows U.S. President George W. Bush's recent decision to pull out of the Kyoto pact.