The four marine surveillance ships were seen moving within 12 nautical miles of the islands, known as the Senkakus in Japan and the Diaoyus in China, just before midday, the coastguard said in a statement.

It was the first time since December 31 -- and the 21st time since Japan nationalised the islands in September -- that any state-owned Chinese ship has been seen in the archipelago's waters, which lie in the East China Sea.

A state-owned Chinese plane flew through airspace over the islands early last month. Tokyo responded by scrambling fighter jets and said it was the first time Beijing had breached its airspace since at least 1958.

On Saturday, another Chinese state-owned plane approached the islands without entering the airspace, prompting another Japanese fighter jet dispatch.