Japanese top government spokesman Osamu Fujimura on Monday voiced regret over a recent trip made by a Russian official to disputed islands off Hokkaido, according to Japanese (Kyodo) News Agency. ''''Our country considers a visit to the Northern Territories by a key Russian government official unacceptable,'''' the chief Cabinet secretary said in a news conference, a day after Russian Security Council Secretary Nikolai Patrushev visited the islands of Kunashiri and the Habomai group of islets. Tokyo and Moscow remain at odds over the sovereignty of the islands of Etorofu, Kunashiri and Shikotan as well as the Habomai islet group, which Soviet troops seized at the end of World War II.