MANILA — The Chinese coast guard boarded Philippine navy vessels and damaged and confiscated equipment in a confrontation that left a sailor severely injured this week, the Philippines announced Wednesday, in a stark escalation of tensions over the highly contested South China Sea.

       According to Philippine officials, Chinese vessels on Monday rammed Philippine ships to stop them from resupplying a warship, the Sierra Madre, beached on a half-submerged reef known as the Second Thomas Shoal, which has become a central flash point in the dispute between the two countries.