The Philippine Coast Guard (PCG) deployed a helicopter to monitor a Chinese research ship passing through archipelagic waters.

Footage shows the aircraft hovering over the research ship, Song Hang, which was sailing 58 nautical miles east of Palawan island, on April 2.

US maritime expert Ray Powell said the 280ft vessel, which is owned and operated by Shanghai Ocean University, departed from Shanghai on March 26. It entered Philippine territory on March 31 and was traversing the Sulu Sea in the southwestern part of the archipelago on April 2 afternoon.

The PCG said in a statement: 'While the vessel is entitled to the right of innocent passage in accordance with the United Nations Convention on the Law of the Sea, the PCG is closely monitoring the vessel's movement to ensure compliance with all relevant domestic and international maritime regulations and to safeguard the country's maritime interests.

'The PCG has directed the deployment of aerial assets to conduct surveillance and provide situational awareness.'

The Philippines and China are embroiled in a long-standing conflict over disputed territories in the South China Sea.

Expansionist China currently lays claim over almost the entire waterway, 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.