China today denounced Japan's decision to name the islets in the disputed territory in the East China Sea, saying any such move to claim the islands is illegal and invalid.
Foreign ministry spokesman Qin Gang said the islands are inherent territory of China.
Japan today named 158 uninhabited islets at the edge of its territorial waters, including a group five islands that is part of an archipelago also claimed by China.
The group of islands, named after directions of the compass and believed to have vast natural resources underneath its seabed, is called Senkaku in Japan and Diaoyu in China.
"The Diaoyu Island and its affiliated islands are China's inherent territory, and China has named them all", Qin said in comments posted on the Foreign Ministry website.
"China is firmly opposed to any act by the Japanese side that undermines China's territorial sovereignty.
"Whatever unilateral measure Japan takes for this end is illegal and invalid, and will not change the fact that the Diaoyu Island and its affiliated islands belong to China."
Japan, which administered the islands till recently, asserts that it is part of the island chain while China, which scaled up its move to secure them since 2012 after Tokyo nationalised them, claims them to be part of its territory since 1895.
The government said that naming the islands is meant to raise public awareness that they belong to Japan.
The claims and counter-claims by Japan and China have inversely affected their bilateral ties.
The two countries aggressively patrol the islands and their have been several standoff over and on the contested territory.
