Beijing has rebuffed a Japanese request that the Chinese government contribute financially to a greenery foundation that supports tree-planting projects in China, a source close to the matter said Saturday.

Japan, which has unilaterally underwritten the projects for years as part of an aid program, wanted both countries to fund the work jointly given China’s economic rise. Japan allocated about ¥9 billion for the foundation in a supplementary budget for fiscal 2015.

The foundation was launched in 1999 as an initiative by then-Prime Minister Keizo Obuchi to increase the number of trees in China. The Japanese government set aside ¥10 billion at the time.

“It is necessary to continue projects (funded through the foundation) to promote friendly ties” between Japan and China, the source said on the reason why the program remains important.

The foundation has funded about 900 projects undertaken by Japanese nongovernmental groups, but its funding had dwindled to about ¥1.5 billion by the end of last June.

A veteran lawmaker in the ruling Liberal Democratic Party recently questioned the funding to the world’s second-largest economy.