A Chinese monster ship left Philippine waters after a five-day standoff with the Philippine Coast Guard (PCG).

China Coast Guard (CCG) vessel 5901 began sailing away from the coastline of Zambales province on January 8.

The garguantuan ship, the world's largest coast guard vessel at 541 feet and 12,000 tons, has been lurking off the seaside province since January 4 afternoon. Another CCG ship was headed to the area to replace it, officials said.

PCG spokesman Commodore Jay Tarriela said in a January 8 statement: 'As of 3 PM today, CCG-3103 was detected by Canada's Dark Vessel Detection at a distance of 60 nautical miles from Pandaquit, Zambales. This indicates that CCG-3103 is likely serving as a replacement vessel for the monster ship, thereby sustaining its illegal presence within the Philippines' Exclusive Economic Zone.'

He added that PCG helicopter has confirmed the Chinese vessel's presence. Philippine ship BRP Cabra was dispatched to monitor its movements.

Authorities believe the CCG 5901 was deployed 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.