Fishermen aboard three vessels with clear Chinese coastguard markings boarded two Philippine fishing boats in Scarborough Shoal on April 11, then took the crew's catch, the Philippine fisheries bureau said.
In one incident, the Filipino fishermen "were threatened and pointed with a gun before the Chinese forcibly took their fishes," according to an incident report from the bureau sent to AFP.
The gunmen also destroyed the Filipinos' fishing equipment, the report said.
A week later three Chinese coastguard ships fired water cannon on a Philippine fishing boat, injuring at least three crewmen and destroying the ship's glass windows, according to a separate report from the bureau.
"This is unacceptable because the area is within our exclusive economic zone," Philippine fisheries bureau head Asis Perez told AFP.
"No country has the right to stop our fishermen from doing their jobs. That's against international law."
Asked about the incidents today, Philippine foreign affairs spokesman Charles Jose said the government would file a diplomatic protest.
China took control of the shoal following a tense standoff between Chinese maritime patrol vessels and the Philippine navy in 2012.
