A Chinese research vessel (CRV) was seen retrieving deep sea equipment during an unauthorised expedition in Philippine waters.

Footage shows the Chinese ship, the Tan Suo 3, collecting a deep-sea submersible called the SHENHAI YONGSHI from the sea off Ilocos Norte, on May 5.

Philippine authorities said the submersible was designed for deep-sea exploration, capable of diving up to 2.8 miles underwater.

A rigid inflatable hull boat was later dispatched from the vessel to retrieve a yellow object believed to be marine research equipment.

The Philippine Coast Guard (PCG) said it sent warnings to the Tan Suo 3 which went ignored.

PCG spokesman Commodore Jay Tarriela said: 'These actions by the CRV clearly indicate that the People's Republic of China is conducting unauthorized marine scientific research activities within the Philippines' Exclusive Economic Zone, lacking the necessary legal authority for such operations.'

The Tan Suo 3 reportedly entered Philippine territory on May 1, and left the Philippine Exclusive Economic Zone on May 5.

The incident comes as Philippine defence chiefs were probing Chinese 'spy drones' - capable of gathering environmental data - around Philippine waters.

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.