The Philippines opened its case against China before an international arbitration tribunal Tuesday, which it hopes will rule in its favour in an increasingly fraught territorial dispute with Beijing over the South China Sea.

"The case has started for the hearing on jurisdiction and admissibility before the arbitral tribunal," a source familiar with the hearing told AFP.

Manila in early 2013 submitted its case to the Hague-based Permanent Court of Arbitration, a 117-state body set up in 1899 to rule in disputes between countries, and private parties including companies.

The Philippines hope to convince a five-member panel of judges and law academics at a closed-door meeting that the PCA has the jurisdiction to hear the case. China is refusing to participate.

If the PCA decides it has jurisdiction, the merits of Manila's case against Beijing's claim over most of the resource-rich sea could be heard at a later round of hearings.

Herminio Coloma, spokesman for Philippines President Benigno Aquino earlier told journalists that Manila is "following its position of seeking a rules-based, diplomatic and peaceful solution."

But China's foreign ministry spokeswoman Hua Chunying told reporters it opposed the arbitration.

"China has on many occasions expounded its position by neither accepting nor participating in the arbitrary procedure unilaterally initiated by the Philippines in breach of (an) agreement repeatedly confirmed with China as well as the Philippines," she said.

"China opposes any moves by the Philippines to initiate and push forward the arbitrary proceedings," Hua said.

The PCA's arbitral tribunal is to issue a ruling, called an "award" after the hearing wraps up on Friday, but it was unknown how long it would take and whether it would be released in public.

The panel's ruling is binding on both parties, according to the PCA's arbitration rules published on its website.

The panel's decision also cannot be appealed and must be carried out without delay, said Aaron Matta, a senior researcher at the Hague Institute for Global Justice.

But "the fact that China is not collaborating with the proceedings, casts doubts regarding the future enforcement of the court's eventual award," Matta told AFP.

Based at the Hague's Peace Palace, the PCA is not under obligation to make its rulings public, but could do so with the consent of all parties or where it has a legal duty to do so.