fishermen in the area of the disputed Spratly Islands, according to sketchy reports reaching Philippine Navy chief Rear Admiral Alexander Pama.
The foreign jet "buzzed" a local fishing boat at the Dalagang Bukid Shoal, located some 131 miles from Balabac Island in Palawan.
Pama said on Monday the reported intrusion occurred between June 2 and June 4. The local fishermen reported that the jet flew some 20 to 30 feet above the fishing boat, "buzzing" the fishermen and scaring them away.
"These fishermen they couldn't identify the jet. They just reported loud sound above them, then they got nervous," Pama said, citing sketchy information reaching him.
Pama said the jet "was definitely not ours."
The Philippines, China, Vietnam, Malaysia, Brunei and Taiwan all claim territory in the South China Sea, which Manila recently started referring to as West Philippine Sea, after China insisted it had sovereignty even over areas included in the Philippines's 200-mile exclusive economic zone.
Earlier, Defense Secretary Voltaire Gazmin said at least six incursions were made by Chinese troops this year, triggering diplomatic protests from the Philippines.