By AFP and Focus | 2026-04-20

The Philippines accused Chinese fishermen of pouring cyanide into the waters of the Spratly Islands, a flashpoint in the disputed South China Sea that has been the site of violent confrontations with Chinese vessels.

Beijing claims the strategic South China Sea in nearly its entirety, despite an international ruling that its assertion has no legal basis.

The Philippines' National Security Council (NSC) alleged on April 13 that the poisoning began last year around Second Thomas Shoal in the Spratly chain, which sits near vital shipping lanes and is reputedly rich in minerals.

"The use of cyanide on Ayungin Shoal is a term of sabotage that seeks to kill local fish populations, depriving Navy personnel of a vital food source," NSC assistant director-general Cornelio Valencia told a news conference, using the Philippines' term for the reef.

These actions also "threaten our Navy personnel" through exposure to contaminated water, consumption of poisoned fish, and the erosion of corals, Valencia added.

Manila and Beijing have a long history of maritime territorial disputes in the hotly contested waterway, including a violent clash in June 2024 in which Chinese coast guard personnel wielding knives, sticks and an axe boarded Philippine Navy boats.

China's Foreign Ministry branded the fresh accusations a "farce."

It is "completely unbelievable and not even worth refuting", spokesman Guo Jiakun told a regular news briefing on April 13.

"The Philippines has illegally harassed Chinese fishing vessels engaged in normal fishing activities, robbing fishing people of their supplies," he added.

Cyanide claims

Although Manila raised the alleged poisoning with Beijing at a recent meeting, Valencia said that the government has yet to receive a formal reply.

He cautioned that such ecological damage threatens the structural integrity of the BRP Sierra Madre, the WWII-era ship housing Filipino troops.

Furthermore, severe reef degradation could allow Beijing to "fabricate an environmental crisis" to blame on the Philippines, a tactic similar to previous Chinese claims that the vessel itself was polluting the shoal.

Manila deliberately grounded the vessel on the shoal in 1999 to stake its claim to the territory.

Philippine Navy spokesman Rear Admiral Roy Vincent Trinidad said Filipino troops had seized 10 bottles of cyanide from sampan boats launched from Chinese fishing ships in February, July and October 2025.

Laboratory analysis by the National Bureau of Investigation's Forensic and Scientific Research Service confirmed that the yellow bottles contained cyanide, a highly toxic chemical capable of causing irreversible damage to humans and marine ecosystems, according to Valencia.

He said that soldiers observed another Chinese sampan crew poisoning waters near the shoal last month, adding that the shoal's waters later tested positive for cyanide.

None of the troops aboard the warship have tested positive for the poison, Trinidad added.

Both officials alleged the fishermen's mother ships worked for the Chinese Navy.

The NSC plans to submit a report next week to the Philippine Foreign Ministry which could become the basis for a diplomatic protest.

Manila has also ordered the navy and coast guard to step up patrols "to prevent further environmental harm" in the area, he added.

Such actions, if proven intentional, would constitute a "blatant violation of Philippine environmental laws, international maritime norms, and state obligations under the United Nations Convention on the Law of the Sea (UNCLOS)," Valencia warned.

He characterized the operation of Chinese vessels using hazardous substances in the area as "both irresponsible and unacceptable," the Philippine News Agency (PNA) reported.

He reiterated Manila’s position, declaring: "The Philippines will not tolerate any act -- whether by state or non-state actors -- that endangers its personnel or the marine environment, violates its sovereign rights, or undermines peace and stability in the West Philippine Sea," according to the PNA.

The government, he said, remains resolute in defending national territory, safeguarding natural resources, and upholding the rule of law.