Japan has protested to North Korea for raising opposition to Tokyo's bid to win a permanent seat on the U.N. Security Council at an informal meeting with other countries, the Japanese mission to the U.N. said Thursday, according to the Kyodo News agency. The Japanese mission said in a statement that Toshio Ozawa, one of Japanese diplomats at the U.N., expressed grave concerns about North Korea's allusion to bilateral matters at an informal meeting Wednesday dealing with U.N. reform, Kyodo said. Ozawa said at the meeting that eligibility for permanent membership should be judged by a nation's contributions to international peace and security, the Japanese mission to the U.N. said, according to the report. Ozawa also criticized North Korea for pursuing a nuclear arms program, the Japanese mission said. Kyodo reported.