MANILA - Philippine Defense Secretary Delfin Lorenzana has raised alarm over China's move to hold military exercises in contested areas in the South China Sea.

"That is very concerning. We view that with alarm. If they did it in their part of the South China Sea, then it's okay," Lorenzana said Wednesday after the Asian superpower recently launched naval drills in Paracels Island that is claimed by China and Vietnam.

Lorenzana added, "But if they are doing it the contested areas then that will, you know, sound the alarm bells for all the claimants here in the South China Sea or West Philippine Sea."

The defense chief noted that the Philippines had conducted military exercises with the American soldiers in the country's territorial waters in the past.

"The Chinese can do theirs in their territorial waters, within their exclusive economic zone and I think that's okay. But if you do it here in the contested area, as I said earlier, then that's highly provocative," Lorenzana said.

He also reiterated his opposition over China's plan of establishing an air defense identification zone (ADIZ) over the South China Sea.

"They should not do that. If they do that and they try to control the airspace and the sea and require others to ask permission to pass through, then that's another story," he said.

Lorenzana revealed there had been a "slight increase" of Chinese incursions and harassment against Philippine government ships and fishing boats recently.

"From August 2019 to early 2020 alone, almost 20 counts of harassment took place, which involved the People's Liberation Army Navy, China Coast Guard, commercial fishing vessels and Chinese maritime militia," he said.

Among them is the aiming of a fire control radar by a Chinese corvette at a Philippine Navy ship near the Philippine-occupied Rizal Reef in February, he said.

China's sweeping claims over almost the entire South China Sea has been invalidated by an international arbitration court in 2016.