The Philippines accused the Chinese coast guard Friday of firing water cannon at a boat carrying provisions to Filipino troops on a remote outpost in the disputed South China Sea. 

"CCG vessel 5203 deployed water cannon against Philippine supply vessel M/L Kalayaan in an illegal though unsuccessful attempt to force the latter to alter course," a Philippine government task force said in a statement.

The latest incident near Second Thomas Shoal in the Spratly Islands comes nearly three weeks after two collisions between Chinese and Philippine vessels during a resupply mission. 

A handful of Filipino troops are stationed on the crumbling BRP Sierra Madre, which the Philippine Navy grounded on the reef in 1999 to check China's advance in the waters.

The troops depend on the resupply missions for their survival.

China claims almost the entire South China Sea, through which trillions of dollars in trade passes annually, and has ignored a 2016 international ruling that its assertion has no legal basis.

Over the past decade or so, Beijing has deployed vessels to patrol the waters and built artificial islands that it has militarized to reinforce its stance.