OSAKA — Antinuclear activists from Japan, South Korea, Europe and the United States called on delegates at the Nonproliferation Treaty Review Conference on Friday to pressure Tokyo to end its troubled Monju fast-breeder reactor program, saying it sets a bad example for the rest of the world and dramatically increases proliferation risks.

"On May 6, Japan's Monju fast-breeder reactor was restarted, after being shut down for over 14 years due to an accident involving a sodium leak and fire. It's a great irony that a plutonium-fueled fast-breeder reactor was restarted at a time when unprecedented international attention is being given to nuclear disarmament, nonproliferation and security," the letter, endorsed by 29 antinuclear groups, reads.

It was presented to delegates at the conference, which is meeting in New York until the end of the month.