President Ferdinand Marcos Jr. said that he would not tolerate China's decision to arrest any foreign nationals trespassing in the South China Sea, including areas within Manila's exclusive economic zone.

In a media interview late Saturday, Marcos strongly condemned Beijing's newly approved policy allowing the Chinese Coast Guard to detain foreign nationals deemed trespassers in disputed waters for up to 60 days without a trial.

State-run China News Service said that Beijing's measure is included in the new regulations issued by the CCG on Wednesday to standardize their law enforcement practices and will be effective starting 15 June.

"That kind of action would be completely unacceptable to the Philippines," Marcos said.

"We will take whatever measures to always protect our citizens," Marcos added, without disclosing specific actions.

The new directive allows the CCG to detain foreigners suspected of violating entry and exit regulations, aiding others in illegal entry or exit, and those with unauthorized residence or employment.

The regulations also permit the detention of individuals "endangering national security and interests, disrupting social and public order, or engaging in illegal and criminal activities," according to an open-source translation tool.

Filipino fishermen have experienced ongoing harassment from Chinese vessels in the disputed waters for years, leading to a significant decline in their livelihoods.

The Philippines has long contested China's expansive territorial claims in the South China Sea, a resource-rich area vital for Filipino fishermen and trade.

A 2016 international arbitration ruling sided with the Philippines in this dispute, a decision China continues to disregard.