Japan's government confirmed three Chinese ships had entered into what Japan considers its territorial waters near disputed islands in the East China Sea.

(SOUNDBITE) (Japanese) JAPANESE CHIEF CABINET SECRETARY OSAMU FUJIMURA SAYING:

"We don't know if China has other intentions (for deploying ships), but we think that they are operating with a single objective. Of course, if they enter our territorial waters, we will raise objections at the highest level."

China's news agency said the two surveillance ships were undertaking a "rights defence" patrol near the islands.

The Japanese coast guard had ordered the ships out of the area, but recieved no response.

China's state television reported Chinese plans to use pilotless aircraft to survey the waters around the disputed islands.

Sino-Japanese relations deteriorated sharply after Japan bought the islands, called Senkaku in Japan and Diaoyu in China.