A China Coast Guard ship reportedly harassed a Filipino fishing boat entering disputed waters in the South China Sea.

Footage shows the Chinese vessel blaring warning sirens as it blocked the much smaller wooden fishing boat headed for a contested shoal, on January 12.

The ship was around 30 metres away as a frustrated Filipino fisherman said: 'We are just trying to make a living. Why is it like this?'

The fishermen changed course to avoid the China Coast Guard but were allegedly chased before they were collected by the Philippine Coast Guard (PCG).

PCG spokesman Commodore Jay Tarriela said: 'According to the Filipino fishermen, their intention was to conduct a fishing expedition. Even before they arrived in that area, the China Coast Guard already started harassing them by dangerous manoeuvres, blocking, and even with the use of sirens.

'We were able to contact the Filipino fishing boat and meet them at a a particular location. We allowed the fishermen to board the Philippine Coast Guard vessel, conducted medical examinations on them, and provided them with food when they boarded. We also gave them fuel for them to sustain their fishing expedition.'

Ryan Jacinto, captain of the FFB Prince LJ boat, said: 'It's a good thing the Philippine Coast Guard was here. Thank goodness they rescued us and moved us away from the Chinese ship.'

The PCG said the fishermen were being guarded by the BRP Cape San Agustin as they resumed fishing near Scarborough Shoal, a disputed reef in the South China Sea, around 120 miles west of the Philippines.

It said the incident is the first instance of alleged harassment in the major territorial flashpoint.

The Philippine Navy said the number of Chinese vessels at the shoal has doubled since December.

Expansionist China currently lays claim to almost the South China Sea, which is 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.