The drills, the statement said, involved firing dozens of missiles and torpedoes and was aimed at bolstering "the assault intensity, precision, stability and speed of troops amid heavy electromagnetic influences," an apparent reference to electronic warfare.

"An information technology-based war at sea is sudden, cruel and short, which requires fast transition to combat status, quick preparation and high assault efficiency," the statement said.

The drill involved naval aviation forces, including submarines, ships and coast guard servicemen.

The statement did not specify where in the waters the military exercises were held.

The East China Sea is home to the Japanese-controlled Senkaku Islands, which are also claimed by China, where they are known as the Diaoyus.

China has ramped up its military and coast guard activity in the waters in recent months, with the Japanese Defense Ministry reporting early last month that fighter jets had been scrambled a record 199 times between April and June in response to Chinese aircraft approaching Japanese airspace.