Chinese naval ships have carried out patrolling and military training in waters off disputed islands held by Japan, the Defense Ministry said Thursday.

Defense Ministry spokesman Yang Yujun confirmed the maneuvers, the state news agency Xinhua said, after Japanese media reported two Chinese naval frigates navigating waters off the small islands in the East China Sea, called the Senkakus by Japan and the Diaoyus by China.

Yang said the islands have been an inseparable part of Chinese territory since ancient times and therefore "Chinese troops perform a duty of military readiness to quickly react to maritime and airspace emergencies and closely work with the departments of maritime surveillance and fishery administration to provide security for the country's maritime law enforcement, fishery production as well as oil and gas development."

In New York, U.S. Secretary of State Hillary Clinton met Thursday with Chinese Foreign Minister Yang Jiechi on the sidelines of the U.N. General Assembly meeting and said it was important to ratchet down tensions over the islands, Reuters reported.

"The secretary ... again urged that cooler heads prevail, that Japan and China engage in dialogue to calm the waters," an aide told reporters. "We believe that Japan and China have the resources, have the restraint, have the ability to work on this directly and take tensions down, and that is our message to both sides." 

Clinton was due to meet Japanese Foreign Minister Koichiro Gemba and South Korean Foreign Minister Kim Sung-hwan in a three-way meeting on Friday. Japan and South Korea, two close U.S. allies, have also seen their relationship rocked in recent months by maritime territorial disputes.