Around 20 demonstrators rallied Tuesday outside the Japanese Embassy in Beijing to protest the Japanese government's "nationalization" of a group of disputed islands . Demonstrators held up placards with slogans expressing opposition to the Japanese government's move and called for defense of the Chinese-claimed, Japanese-controlled Senkaku Islands, which are known in China as Diaoyu, (Kyodo) news agency reported. The protest came on the same day the Japanese government purchased most of the islands from a Japanese family that owned them, bringing all of the territory under state control. China urges Japan to immediately revoke its wrong decision and stop all actions that undermine China's territorial sovereignty, according to (Xinhua) news agency. As a countermeasure, the Chinese government announced the base points and baselines of the territorial waters of the Diaoyu Islands, which is in accordance with China's law on territorial seas and adjacent zones adopted in 1992, Xinhua added.