Three Chinese maritime surveillance ships entered Japanese territorial waters near the disputed Senkaku Islands in the East China Sea on Thursday morning, the Japan Coast Guard said.

It is the first time in four days that Chinese government ships have entered Japanese waters.

The Chinese vessels entered the area shortly after 7 a.m. Responding to the coast guard's warning not to enter Japanese waters, one of the vessels replied by radio that the Senkakus have been Chinese territory since ancient times, according to the 11th Regional Coast Guard Headquarters in Naha, Okinawa.

Two fisheries patrol vessels were also spotted traveling just outside Japan's territorial waters.

China in recent decades has claimed sovereignty over the uninhabited islets, which Japan placed under its control in 1895.

Prime Minister Shinzo Abe on Thursday called for Beijing to make efforts to improve relations with Tokyo.

"Japan has left the door open at every level," he said before the Diet. "We want to restore a relationship under which we can have frank discussions."