Four China Marine Surveillance ships - the Haijian 51, 26, 66 and 137, are patrolling waters near the Diaoyu Islands, the State Oceanic Administration said on Monday.

The patrols off the Diaoyus started in September when Japan announced its "purchase" of the islands.

Two destroyers and nine other former navy vessels are being transferred to the China Marine Surveillance maritime surveillance fleet, according to the International Herald Leader.

A China Marine Surveillance source told China Daily this fleet will be dramatically expanded, but declined to disclose details.

China Marine Surveillance said early in 2012 that about 36 inspection ships are expected to join the surveillance fleet this year.