Japan and the United States plan to launch a project to preserve rain forests in Africa and Asia, sources at the summit on sustainable development here said Tuesday.

The governments of developing African and Asian countries, environmental organizations and international institutions are to take part in the project, the sources said.

The project will be included in a partnership initiative plan to be announced in the top leaders' meeting of the World Summit on Sustainable Development that will be held for three days beginning Monday, the sources said.

Under the plan, the countries and their partners will ultimately implement a system whereby timber-exporting countries would mark their timber to show it came from appropriately controlled forests, they said. The purpose of the system is to eliminate products made with illegally logged timber.