Japan was planning to notify the U.N. conference on climate change later Tuesday that it wants to achieve a cut of between 3.2 percent and 3.7 percent in carbon dioxide emissions -- more than half of its 6 percent reduction target -- through forest absorption, government sources said Tuesday.

Japan is required under the 1997 Kyoto Protocol to reduce carbon dioxide and other greenhouse gases by 6 percent from 1990 levels between 2008 and 2012.

However, the protocol allows industrial countries to include increases in carbon dioxide absorption by forests through activities such as afforestation.