Japan and China will request next week that a U.N. organization give them five more years to complete a Japan-led project to collect and dispose of abandoned wartime chemical weapons in China, Japanese government sources said Sunday.

The two governments will request the Organization for the Prohibition of Chemical Weapons to extend the deadline to spring 2012 because there are an estimated 300,000 to 400,000 shells still in Dunhua, Jilin Province, left by the Imperial Japanese Army at the end of World War II, they said.

Japan has collected and disposed of about 40,000 shells in China since 2000 under the Chemical Weapons Convention, but large portions of the abandoned shells remain untreated in the Harbaling area in Dunhua due to a delay in constructing essential disposal facilities in the area.

The Chinese government has not signed off on the Japanese government's plan to build the facilities in the city. The Cabinet Office has cited the Chinese side's difficulty in deciding which administrative branch will deal with the unprecedented project.

The convention, which came into force April 29, 1997, requires contracting states to remove within a decade chemical weapons they left in other contracting states.

Contracting states can extend the deadline by submitting a request a year before the deadline.

Japan and China agreed in July 1999 that Japan would provide money, technology and facilities to collect and dispose of abandoned weapons within China.