A Chinese navy frigate is seen on the horizon in waters close to the Haiyang Shiyou 981, known in Vietnam as HD-981, oil rig in the South China Sea July 15, 2014. (Reuters)
The US State Department said on Tuesday that if reports that China used water cannon on Philippine fishing boats in disputed waters are accurate, it would be a provocative step.
"It would represent a step backward in finding a diplomatic resolution to the dispute," State spokeswoman Marie Harf said.
Filipino activists have accused China's coast guard of turning water cannons on civilian boats in the disputed area on Monday.
© Thomson Reuters 2015