An unidentified foreign plane harassed a group of Philippine fishermen in the South China Sea last month in the latest incident in the disputed waters, the Philippine navy said Tuesday.
The fishermen reported the jet flew low over their boat early last month off the Investigator Northeast Shoal, said navy chief Vice Admiral Alexander Pama.
"An unidentified jet buzzed our fishing boat some 20 to 30 feet (6-9 metres) from the top of the mast of the fishing boat," Pama told reporters.
"They were unable to identify the jet; they just said it was noisy and it made them nervous," he said, adding: "Definitely it's not ours."
Asked about the plane's motive, Pama said it was not usual for an aircraft to fly so low over a boat, "so initially it's some sort of a warning, like, 'What are you doing here?'"
The navy said the incident occurred near a shoal claimed by the Philippines that lies between the major western Philippine island of Palawan and the disputed Spratly islands, which are believed to sit on vast mineral resources.
It was the second report of foreign aircraft activity in Philippine-claimed areas of the South China Sea this year.
In May two Philippine air force turboprop planes on patrol near the Spratlys reported two unidentified jets streaking high above them.
Tensions in the strategic and resource-rich South China Sea have escalated in recent weeks, with the Philippines and Vietnam voicing alarm at what they say are increasingly forceful Chinese actions there.
They include Philippine accusations of Chinese forces opening fire on Filipino fishermen, shadowing an oil exploration vessel employed by a Philippine firm, and putting up structures in areas claimed by the Philippines.
Aside from the Philippines, China and Vietnam, the Spratlys are also wholly or partially claimed by Brunei, Malaysia and Taiwan.
Philippine foreign department spokesman Raul Hernandez declined to comment on the navy's allegation, telling AFP he had yet to see the formal report.