TOKYO, August 8 (Itar-Tass) - Japan’s Foreign Ministry summoned on Thursday the Chinese ambassador to express “a strong protest” against China’s activity near the disputed Senkaku (Diaoyu) Islands, according to the ministry’s release.

Japan’s protest evoked after several cases when Chinese marine police vessels entered the islands’ zone that Japan regards as its territorial waters. Such cases have become more frequent recently. Thus, on Thursday, four Chinese ships entered the waters of the archipelago and are staying there up to now. “We have expressed our anger to the Chinese side and pressed for an immediate exit of all the ships,” Foreign Minister Fumio Kishida stressed at a press conference.

Chief Cabinet Secretary Yoshihide Suga said for his part: “This intrusion into territorial waters is the longest since last September’s (state) purchase of the Senkakus and is extremely regrettable. It is totally unacceptable.”

The territorial dispute over the Senkaku (Diaoyu) Islands between Japan and China escalated after Tokyo announced in early September 2012 the purchase of the islands from private owners. After that massive anti-Japanese violent protest arose in China. The past few months, China’s patrol ships are almost permanently present near Senkaku and from time to time demonstratively enter the coastal zone for a short time. Since late July, ships of China’s new unit - marine police that was established on July 23 this year, have been entering this area.