Three China Coast Guard vessels briefly intruded into Japanese territorial waters around the Senkaku Islands in the East China Sea, the Japan Coast Guard said Sunday.

The intrusion, the 22nd of its kind this year, occurred at around 10 a.m. and the ships left the waters about two hours later, the JCG said.

Chinese ships last entered the waters near the uninhabited islands on Wednesday.

China and Taiwan claim the Senkaku Islands, calling them Diaoyu and Tiaoyutai, respectively.

China stepped up its claim to the islets after Japan purchased three of them from a Japanese individual and put them under state control in 2012.