The Philippines on Friday accused Beijing of engaging in the "de facto occupation" of a disputed shoal in the South China Sea, following a face-off that began last year.

Foreign Secretary Albert del Rosario said three Chinese government ships remained in the vicinity of the Scarborough Shoal, scaring off local fishermen.

"The Chinese have tried to establish a de facto occupation," he told reporters.

The Philippines says the shoal is well within its 200-nautical-mile exclusive economic zone, as recognised by international law.

However China insists the shoal is Chinese territory as part of its claim to almost all of the South China Sea -- including waters up to the coasts of other countries.

A face-off between the two countries began last year when China dispatched government vessels to stop the Philippines from arresting Chinese poachers in the area.

He said the Philippines tried to settle the matter through talks but when this failed, it was forced to ask a UN tribunal to strike down China's claims.

Del Rosario also said the Philippines had put off granting oil exploration contracts in disputed waters in the South China Sea due to the "sensitivity of the situation" with China.

"We have given this significant thought and decided what is best for the country. We also don't want to put (private companies) in a compromising situation," he added.

The Philippines has accused China of using intimidation to press its claims in the South China Sea, which are believed to encompass vast mineral resources and also include vital shipping lanes.

Taiwan, Brunei, Vietnam and Malaysia also claim parts of the South China Sea.

The rival claims have for decades made the waters one of Asia's potential military flashpoints.