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.

In 1998, the government said it wanted a 3.7 percent cut in carbon dioxide emissions to be attributed to absorption. However, if forest absorption is interpreted more strictly, the amount will only be 3.2 percent.

The Environment Agency will consult with other ministries and agencies concerned before submitting the report to the conference's secretariat, located in the German city of Bonn, later in the day.

By Tuesday, parties to the U.N. conference on climate change are to submit lists of activities they believe should be included in calculating reduction targets, as well as the proportion to be attributed to means such as absorption.

The official criteria for "sinks" -- methods such as the use of forests and land to absorb carbon dioxide -- will be decided at the sixth Conference of Parties to the U.N. Framework Convention on Climate Change, to be held in November in The Hague.

Japan had been working to expand the use of forest absorption to secure the maximum 3.7 percent cut through sinks.

The use of sinks is controversial as it will enable some countries to virtually meet their greenhouse gas reduction goals without implementing measures to actually cut output.

If the conference establishes a more limited interpretation of sinks, Japan will be required to seek other ways to achieve the remaining 0.5 percent carbon dioxide cut, the sources said.