Japan was urged Thursday to postpone indefinitely a plan to operate a plutonium-reprocessing plant that could produce 8 metric tons of plutonium a year or the equivalent of 1,000 nuclear bombs, dpa reported. The demand was made by the Union of Concerned Scientists, which presented a petition in New York urging the Japanese government not to proceed with plans to activate the plant, situated in the northern region of Rokkasho. The petition, signed by 27 scientists, said Japan would strengthen the Nuclear Nonproliferation Treaty (NPT) and its commitment to disarmament if the plant were to remain closed. Operations at the 20- billion-dollar plant are slated to begin in 2007. Japan is one of the 188 governments that have signed the NPT. Those countries are now holding a month-long conference at U.N. headquarters in New York to review the treaty's effectiveness. "We are calling on the Japanese government to breathe a new life into the NPT by suspending its provocative plan to open the Rokkasho reprocessing plant," said Kurt Gottfied, chairman of the scientist group and a physics professor at Cornell University. --More 0003 Local Time 2103 GMT