Filipino Coast Guard officers demanded Chinese vessels to leave the Philippine coastline.

Crew of the Philippine Coast Guard (PCG) BRP Teresa Magbanua issued radio challenges to China Coast Guard (CCG) 3304 seen 'exhibiting erratic movements' around 80 nautical miles off Zambales province on January 9.

PCG spokesman Commodore Jay Tarriela said in a statement: 'The crew made it clear that the Chinese vessels do not possess any legal authority to patrol within the Philippines' Exclusive Economic Zone and directed them to depart immediately.

'Of particular note during today's operations was the replacement of Chinese Coast Guard vessel 3103 by vessel 3304 in the afternoon. Despite this change, the objective of the Chinese deployment remains the same: to assert normalization and legitimacy in these waters. The PCG is steadfast in its mission to counteract these efforts and prevent any normalization of illegal deployment of CCG vessels.'

CCG 3103 had replaced the Chinese 'monster ship' CCG 5901 seen lurking in the same area over the weekend.

Authorities believe the presence of Chinese vessels was meant to intimidate Filipino fishermen from entering the Scarborough Shoal, a disputed fishing ground and resource-rich area in 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.