MANILA: Joint naval exercises held frequently by the Philippines, United States and other Western powers are helping rein in "aggressive" Chinese actions in the South China Sea, a Filipino military official said on Wednesday (Nov 6).

Beijing has for years sought to expand its presence in the disputed waterway, brushing aside an international ruling that its claim to most of the sea has no legal basis.

In recent months, China has deployed navy, coast guard and so-called maritime militia forces – allegedly Chinese fishing vessels – in a bid to bar the Philippines from a trio of strategically important reefs and islands in the South China Sea.

But those efforts were absent during the 10 instances this year when the Philippines, United States and others were conducting joint patrols dubbed Multilateral Maritime Cooperative Activity (MMCA), the Philippine Navy said on Wednesday.

"During the conduct of MMCAs, there have been no observed coercive and aggressive actions by the (People's Liberation Army) Navy, Coast Guard or the maritime militia," Rear Admiral Roy Vincent Trinidad, spokesman for South China Sea issues, told reporters on the sidelines of a Manila security forum.

The lull was observed for "a few days before and during, and a few days after" the exercises, he said, adding more joint naval drills could be expected in 2025.

Violent encounters with Chinese vessels typically occur during Philippine resupply missions to its remote garrisons in the area.

In Beijing, foreign ministry spokeswoman Mao Ning stressed "China has sovereignty over the South China Sea islands and their adjacent waters" and "we safeguard our sovereign rights and interests in accordance with domestic and international law".

She added: "Making a show of force and provoking confrontation in the South China Sea will only escalate tensions and undermine regional stability."

While Washington and its allies have avoided taking sides in the territorial dispute, they say Chinese actions threaten freedom of navigation essential for trade, with trillions of dollars passing through the waterway each year.

Multilateral and bilateral naval exercises help "buy time as we continue developing our capabilities", Trinidad said Wednesday, noting it was a "great challenge" given the Philippine military's limited equipment.

He also said that the Association of Southeast Asian Nations, which groups Manila and nine neighbours, was "not doing enough" to support the Philippines or international law.

Fellow ASEAN members Brunei, Indonesia, Malaysia and Vietnam also have claims overlapping Beijing's in the South China Sea, but others in the bloc have closer ties with China.

Trinidad urged ASEAN countries not to "suffer in silence" in the face of Chinese actions.