The Philippines discovered cyanide on Chinese boats operating around a disputed atoll in the South China Sea, security officials from the country said on Monday.

Authorities ?said laboratory tests confirmed the presence of the highly toxic substance in bottles ?seized by ?the Philippine navy in operations at Second Thomas Shoal last year.

Officials warned ?that the cyanide could have had serious consequences for marine life and weakened the reef supporting a warship that Manila grounded on the atoll to reinforce its maritime claim.