The Philippine Coast Guard (PCG) deployed an aircraft to monitor a Chinese research vessel lurking near the country's northernmost province.

Footage shows the plane issuing a radio challenge to the Xiang Yang Hong 05 ship spotted just 15 nautical miles off the Philippine island of Babuyan on Saturday afternoon.

The area is part of the Luzon Strait - a key naval chokepoint between Taiwan and the Philippines.

PCG spokesman Commodore Jay Tarriela said in a statement: 'The PCG aircraft successfully conducted its MDA flight yesterday afternoon and physically sighted the Xiang Yang Hong 05 at a distance of 14.92 nautical miles from Babuyan Island. The vessel was challenged by the PCG aircraft but did not respond.

'Notably, the Xiang Yang Hong 05 had previously departed from Guangdong province, China, on June 5, 2025, en route to the West Philippine Sea. It entered the Philippine Exclusive Economic Zone on June 7, approximately 130 nautical miles from Burgos, Ilocos Norte, and subsequently left on June 9, only to re-enter the EEZ last July 31.'

It was last detected via Automatic Identification System, sailing 86 nautical miles off Calayan Island in Cagayan on Sunday morning.

Philippine authorities said the research vessel had spent 22 days travelling along a parallel track in the Pacific Ocean close to Guam.

Alarmed officials have been flagging Chinese research ships in recent months, including one seen retrieving deep sea equipment near Ilocos Norte province on May 5.

The Philippines is currently embroiled in a territorial dispute with China over parts of the South China Sea.

Expansionist China currently lays claim over almost the entire South China Sea, one of the world's busiest sea lanes. But a United Nations-backed tribunal in 2016 deemed its claims groundless.

The Communist rogue state - accused of genocide for its crimes against the Uyghur population - has been steadily increasing its influence in recent years through investment in developing countries.