The specialised radar provides precise targeting coordinates to a ship's weapons systems.

Chinese and Philippine ships regularly clash in the crucial waterway, which Beijing claims nearly in its entirety, despite an international ruling that its assertion has no legal basis.

The latest alleged incident took place on March 7 near the flashpoint Sabina Shoal, a fish-rich area about 150 kilometres (90 miles) from the Philippine island of Palawan, the Philippine Navy said in a statement.

The BRP Miguel Malvar was patrolling the area when "a PLA Navy vessel, with bow number 622 ... approached and later directed its fire control radar toward the Philippine Navy ship," the Philippine Navy said Friday.

"This was an alarming and provocative action that created unnecessary risk and could have led to misinterpretation and misunderstanding at sea," the statement added.

The Chinese Embassy in Manila did not immediately respond to a request for comment.

The two countries traded statements earlier this month claiming sovereignty over the Scarborough Shoal, a traditional fishing area for Filipino fishermen now controlled by China.

In October, Manila accused a Chinese ship of deliberately ramming one of its government vessels after first deploying water cannon in the South China Sea's disputed Spratly islands chain.