The Philippines has accused Chinese fishermen of dumping cyanide in waters around the Spratly Islands, a fiercely contested area in the South China Sea. Manila described the alleged poisoning as an act of 'sabotage' on Monday, intended to 'kill local fish populations' and deprive Filipino troops stationed at Second Thomas Shoal of a crucial food source.

China dismissed the claim as a 'farce'. The allegation follows years of tense stand-offs and occasional violent confrontations between Philippine and Chinese vessels in the disputed waters. The South China Sea is at the centre of a territorial dispute between China, the Philippines and other countries.

Chinese foreign ministry spokesman Guo Jiakin said the accusation was 'completely unbelievable and not even worth refuting'. 'The Philippines has illegally harassed Chinese fishing vessels engaged in normal fishing activities,' he added.

The Philippine National Security Council (NSC) said the alleged poisoning began last year around Second Thomas Shoal, part of the Spratly archipelago. The reef is home to a small Philippine military outpost aboard the BRP Sierra Madre, a rusting World War Two-era ship that was deliberately grounded there in 1999 to assert Manila's claim to the territory.

NSC assistant director-general Cornelio Valencia stated that the use of cyanide was intended to 'kill local fish populations, depriving Navy personnel of a vital food source'. He told a press conference that it also posed health risks to troops by contaminating the water and fish, and could damage the coral reefs that help support the vessel's structural foundations.

Valencia added that Manila raised the alleged poisoning with Beijing at a recent meeting but received no formal response. The NSC intends to submit a report to the foreign ministry that could form the basis of a diplomatic protest. The navy and coastguard have been ordered to increase patrols in the area.

Philippine Navy spokesman Rear Adm Roy Vincent Trinidad detailed that Filipino troops seized 10 bottles of cyanide from sampan boats allegedly launched from Chinese vessels in February, July, and October of last year. He noted that military personnel spotted another Chinese sampan crew poisoning waters near the shoal last month, and subsequent tests confirmed the presence of cyanide.

The illegal use of cyanide in fishing has historically devastated marine ecosystems in parts of Southeast Asia. The South China Sea, with overlapping territorial claims from China, the Philippines, Vietnam, Taiwan, Malaysia, and Brunei, serves as a crucial shipping route and provides vital fishing grounds for millions.

Additionally, the region is believed to contain significant natural resources and energy reserves, heightening the stakes in these ongoing territorial disputes. Despite a 2016 international tribunal ruling that denounced China's expansive claims as baseless, Beijing continues to reject it, asserting sovereignty over nearly the entire sea.