A Russian attack submarine sparked alarm when it surfaced in Philippine waters in an apparent show of solidarity with rogue state China.

The Russian Navy's UFA 490 emerged some 80 nautical miles west off Occidental Mindoro province on November 28.

In a statement, the Armed Forces of the Philippines said assets were immediately deployed to monitor the submarine after it was seen.

The AFP said: 'The Russian vessel stated it was awaiting improved weather conditions before proceeding to Vladivostok, Russia. Philippine naval forces, including FF150, escorted and monitored operations to ensure the submarine's compliance with maritime regulations within the Philippine Exclusive Economic Zone (EEZ).'

The Russian sub, which was reported to have Kalibr missile firing capabilities, had arrived from Malaysia and did not submerge as it moved northward over the weekend.

Philippine President Ferdinand Marcos Jr. described the sighting as 'very concerning'.

He said: 'Any intrusion into the West Philippine Sea, of our EEZ, of our baselines, is very worrisome.'

Russia is a known political ally of China, with which the Philippines is currently embroiled in a territorial dispute over parts of 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.