Philippine biologists claim they discovered degraded corals amid China's alleged artificial island building activities in disputed parts of the South China Sea.

An underwater survey revealed 'a pile of sand and rubble' believed to be products of island-building activities near Pag-asa Island, around 300 nautical miles from the Philippine island of Palawan, Biology Professor Jonathan Anticamara of the University of the Philippines said in a media forum on May 4.

He said: 'The pile of sand and rubble on Pag-asa Cays 1, 2 and 3 have many characteristics that are atypical of naturally formed coral or sandy barrier islands, indicating that these are possibly product of island building activities that are observed in WPS, but with some degree of uncertainty.'

Philippine Coast Guard Spokesman Jay Tarriela said he believed China was behind the 'illegal small island reclamation'.

He added: 'Only China has access to these cays, which are located near their reclaimed military base on Subi Reef. Additionally, Chinese Coast Guard and Chinese Maritime Militia are frequently observed swarming these cays.'

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.