After months of wavering and foot-dragging, Japan will seek ratification of the 1997 Kyoto Protocol on curbing global warming during a 150-day ordinary Diet session that is to open in January, government sources said Thursday.

The long-awaited move by the world's second-largest economy -- which ostensibly holds the swing vote on the future of the landmark environmental pact in the wake of the United States' withdrawal -- will likely kick the protocol into force by the end of 2002.

The sources said that Deputy Chief Cabinet Secretary Teijiro Furukawa already instructed senior officials of government ministries concerned to make behind-the-scene preparations for domestic measures, including legislative changes, that would become necessary for Japan to implement the pact.