A helicopter tries to save a fisherman during a joint exercise by civilian maritime authorities and the People’s Liberation Army Navy in the East China Sea on Friday.[Zhang Lei / For China Daily]

China on Friday held a large-scale drill simulating the PLA protecting Chinese administration ships disturbed by foreign ships in the East China Sea.

The drill comes amid a festering territorial dispute with Japan.

When asked about the exercises, the Foreign Ministry said on Friday that Beijing is determined to protect its territory and called on Japan to return to negotiations.

The exercise is likely a hard-line response from Beijing to a joint US-Japan drill targeting the Diaoyu Islands, experts and media have said.

Friday's drill involved all the major Chinese maritime forces, from warships to maritime patrol and fishery administration ships.

A fleet of 11 vessels and eight aircraft participated in the one-day drill. According to reports, the navy sent at least two missile destroyers as well as fighter planes and a hospital ship.

It was based on the scenario of the navy sending warships and aircraft to protect Chinese law enforcement ships damaged in deliberate collisions by foreign ships in the East China Sea.

The drill was announced by Xinhua News Agency late on Thursday.

China has previously sent maritime surveillance ships and fisheries patrol vessels to waters near the islands as the territorial row escalated.

On Tuesday, Japanese military aircraft spotted seven Chinese warships not far from the disputed islands. China said the ships were on a routine training mission.

Xinhua said patrol vessels from the fishery administration and the marine surveillance agencies have recently been stalked and harassed by foreign vessels while carrying out missions.

Hong Kong-based Wen Wei Po quoted a military critic as saying that the"high-profile notice" of Friday's drill is very rare as the PLA usually announces its exercises a few days after the actions finish.

It is deliberately showing China's law enforcement capabilities in the East China Sea, it said.

Xia Ziming, deputy head of the Directorate of Operations of the East China Sea Fleet headquarters, told China National Radio that this is the first time for the navy, maritime surveillance and fishery administration agencies to have a joint drill.

“It is the largest one in recent years," Xia said.

The Ministry of National Defense also posted reports high on its website, though it has yet to comment directly on the drill.

When asked about the exercise, Foreign Ministry spokesman Hong Lei on Friday gave no direct answer, but said the Chinese government"is resolute and determined to safeguard national territorial sovereignty".

Japan should be the one to take the responsibility for the escalating tensions, Hong said at a daily briefing.

“We hope the Japanese side can squarely face the realities, correct mistakes and come back to the track of resolving the Diaoyu Islands dispute through negotiations," Hong said.

Smooth coordination between military and civilian organs is the most prominent feature of this drill, Song Xiaojun, a military affairs commentator, told China Central Television.

“China hopes to solve maritime disputes through peaceful negotiations, while such peaceful means is actually based on our administrative bodies' and navy's capabilities to handle security issues," he said.

It's rare but important for the aircraft to join the"multi-dimension" drill as information sharing and coordination between vessels and aircraft should be improved, said Li Jie, a researcher from the Naval Military Studies Research Institute.

“Various law enforcement forces have to properly work together as maritime rights can hardly be safeguarded solely by the navy now," he said.

Feng Wei, an expert on Japanese studies at Fudan University in Shanghai, said the drill has sent a clear warning signal to Japan.