Tokyo, Jun 9 (IANS): Japan on Thursday protested after a Chinese frigate entered the waters near a disputed island chain in the East China Sea.

A Japanese Navy destroyer detected the Chinese ship as it entered the contiguous zone -- an area stretching 24 nautical miles out from the edge of territorial waters -- around Senkaku, also known as Diaoyu, islands, Defence Ministry spokesman Yoshitomo Morii told CNN.

This was the first time a Chinese frigate entered the contiguous zone, he said.

"We're deeply concerned that Chinese naval ships entered the waters contiguous to our Senkaku islands for the first time," Japan's Chief Cabinet Secretary Yoshihide Suga said.

"We, in coordination with the US and the international community, strongly demand China not repeat such behaviour that unilaterally heighten tensions."

According to Japanese officials, Foreign Minister Vice Minister Akitaka Saeki summoned China's ambassador, Chen Yonghua, to lodge a protest "with serious concern".

Morii said the Chinese ship left the area after repeated calls for it to do so by the Japanese vessel.