Chinese naval and air forces conducted patrols around a flashpoint reef in the South China Sea on Saturday, after a slew of tense encounters with countries including the Philippines in the disputed waterway in recent months.

Beijing claims almost the entire South China Sea, brushing off rival claims of several Southeast Asian countries, the Philippines among them, and an international ruling that its assertion has no legal basis.

Its claims include the waters around Scarborough Shoal -- which Beijing seized from Manila in 2012 -- where the Chinese military's Southern Theater Command said Saturday it had held air and sea patrols.

Patrols of the area are typically conducted by the China Coast Guard.

The triangular chain of reefs and rocks is 240 kilometres (150 miles) west of the Philippines' main island of Luzon and nearly 900 kilometres from the nearest major Chinese land mass of Hainan.

Beijing said the training activities around the shoal included "reconnaissance, early warning, and air-sea patrols".

"Certain countries outside the region are stirring up trouble in the South China Sea, creating instability in the region," the Southern Theater Command said in a statement.

"China holds indisputable sovereignty over Huangyan Island and its adjacent waters," it added, using the Chinese name for Scarborough Shoal.

Tensions between China and the Philippines have flared in the past few months during a series of confrontations in the waters also around the contested Second Thomas Shoal and Sabina Shoal.

In July, the two sides said they had reached a provisional deal on resupply missions to a Philippine ship, the Sierra Madre, which is grounded on the Second Thomas Shoal with a garrison on board, aimed at asserting Manila's claims to the reef.

Beijing said Friday it had "supervised" a Philippine ship as it delivered supplies as part of a resupply mission to a grounded vessel at the shoal.