China has accused Japan of a "severe provocation" after Tokyo moved to take over a lighthouse built years ago by right-wing activists on a small, disputed group of islands in the East China Sea. An unidentified official from the Foreign Ministry's Asian department had made solemn representations to the Japanese over the incident, the ministry said in a statement seen on its Web site (www.fmprc.gov.cn) on Saturday. "Japan's actions are a severe provocation and infringement on China's territorial sovereignty and are absolutely unacceptable by the Chinese government and people," the official said. "The unilateral moves taken by the Japanese side are illegal and invalid," the official added, echoing a statement by Foreign Ministry spokesman Kong Quan on Wednesday. The official reiterated China's claims to sovereignty over the islands, known to Chinese as the Diaoyu islands and to Japanese as Senkakus, saying "China has irrefutable sovereignty over all these islands". In Tokyo, Chief Cabinet Secretary Hiroyuki Hosoda told a news conference on Wednesday that Japan's Coast Guard would take over maintenance and management of the lighthouse, adding that the group who built it had given up their rights to it. Despite growing economic interdependence, bilateral ties have been chilled by Japanese Prime Minister Junichiro Koizumi's visits to a Tokyo shrine which honours war criminals along with other war dead. Territorial disputes and a Chinese nuclear submarine's intrusion into Japanese waters in November are other irritants.