Japan will review a plan to push for allowing signatory nations to the 1997 Kyoto Protocol to partially achieve mandated carbon dioxide cuts through forest absorption, government sources said Wednesday.

The government set a goal of absorbing more than 50 percent of its mandated carbon dioxide reduction through forests. The plan is being reviewed to prevent other nations from being discouraged from implementing alternative measures to reduce greenhouse gases.

Japan, which is required by the Kyoto Protocol to cut carbon dioxide and other greenhouse gases by 6 percent from its 1990 levels between 2008 and 2012, had considered seeking increased use of forest absorption to achieve the cuts.

The decision to drop the suggestion was made because, were it applied, it would be unnecessary for countries with vast land areas, such as the United States and Russia, to effectively reduce their output of gases, the sources said.

The protocol, adopted by around 160 countries in Kyoto in December 1997, only allowed countries to include cuts in carbon dioxide achieved by afforestation since 1990 in their reduction targets. However, the option of increasing the portion of cuts allowable through forest absorption was left open to discussion.

The official criteria for the percentage of cuts allowable through sinks -- 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 achieve carbon dioxide cuts through international negotiations to 3.7 percent.

However, it later discovered that some countries, including the U.S. and Russia, will nearly be able to meet their reduction commitments by forest absorption only.

The reduction target for the U.S. is 6 percent and Russia must maintain its emissions at the 1990 level. Parties to the U.N. conference on climate change are scheduled to submit by Aug. 1 lists of activities they want approved to reduce carbon dioxide emissions and the percentage of the reduction goal for each activity, according to the sources.

The Environment Agency and the Forestry Agency have been working on data to be submitted and Japan is likely to drop its goal of a 3.7 percent reduction in carbon dioxide emissions through forest absorption to 2 percent, the sources said.