China has indisputable sovereignty over the Scarborough Shoal and its adjacent waters, and has always resolutely countered infringements by the Philippines, a spokesperson for China Coast Guard said in a statement released late Tuesday.

 A China Coast Guard ship is seen from a Philippine fishing boat at the disputed Scarborough Shoal.

The spokesperson said four Philippine personnel illegally intruded in certain areas on Jan. 28, and the Coast Guard warned them to leave in accordance with the law. The interaction was "professional and standardised", according to the statement.

Accusations and runs-in have occurred frequently between the two countries over the past year over disputed territorial areas of the South China Sea.

China claims sovereignty over almost the entire South China Sea, which has angered neighbouring countries that dispute some boundaries they say cut into their exclusive economic zones.

"China's Coast Guard will, as always, defend and enforce" the law in waters under the country's jurisdiction, the statement said, citing the spokesperson.

China routinely conducts patrols of the South China Sea even as tensions simmer between it and the Philippines, which recently had its own joint military patrol in the region with its ally - the United States - drawing the ire of China.

The spokesperson said the Coast Guard will firmly safeguard national sovereignty and maritime rights and interests.