BEIJING — The Philippines and China exchanged accusations of intentionally ramming coast guard vessels in disputed waters of the South China Sea on Saturday, the latest in an escalating series of clashes in the vital waterway.

The collision near the Sabina Shoal was their fifth maritime confrontation in a month in a longstanding rivalry.

Beijing claims almost the entire South China Sea, including parts claimed by the Philippines, Brunei, Malaysia, Taiwan and Vietnam. Portions of the…