Japan lodged two protests Sunday as 13 Chinese government vessels were spotted in waters around the Senkaku Islands in the East China Sea. The islets, also claimed by China, are known as the Diaoyus.

The number of vessels, located in a contiguous zone just outside Japanese territorial waters, was a record since the Japanese government purchased most of the islands from a private owner in September 2012. The previous record of 12 was logged shortly after the purchase.

Two China coast guard ships among the vessels entered Japanese territorial waters in the morning. During the afternoon, four ships entered the waters, according to Japan Coast Guard officials.

Six of the 13 vessels were armed and many Chinese fishing boats were spotted near the territorial waters, it said.

Vice Foreign Minister Shinsuke Sugiyama lodged a protest with Chinese Ambassador to Japan Cheng Yonghua, saying the maritime activity was in violation of Japanese sovereignty and unacceptable, according to the Foreign Ministry.

On Saturday, around 230 Chinese fishing boats and seven coast guard vessels were spotted in the contiguous zone around the disputed islands, prompting Tokyo to protest to Beijing.