China has no legal basis to claim "historic rights" to islands in the South China Sea and has violated Manila's sovereign rights, an international tribunal ruled on Tuesday, in a bitter dispute that risks stoking further tensions in Southeast Asia.

"The tribunal concluded that there was no legal basis for China to claim historic rights within the sea areas falling within the 'nine-dash line'," The Hague-based Permanent Court of Arbitration said in a statement.

Manila -- which had lodged the suit against Beijing in 2013 -- welcomed the ruling but China reacted furiously, saying it "does not "accept and does not recognise" the decision.

Beijing had refused to participate in the case, saying the tribunal had "no jurisdiction" over the issue.

Beijing claims most of the South China Sea, even waters approaching neighbouring countries, as its sovereign territory, basing its arguments on Chinese maps dating back to the 1940s marked with a so-called "nine-dash line".

But in its hard-hitting ruling, the PCA said Beijing "had no historic rights to resources in the waters of the South China Sea" and that "such rights were extinguished to the extent they were incompatible with the exclusive economic zones provided for in the Convention", referring to the UN Law of the Sea.

"China had violated the Philippines' sovereign rights in the exclusive economic zone by interfering with Philippine fishing and petroleum exploration, by constructing artificial islands and failing to prevent Chinese fishermen from fishing in the zone," the PCA said.

The tribunal further ruled that the disputed Spratly islands "cannot generate maritime zones collectively as unit" as claimed by China.

Tuesday's judgement comes against the backdrop of frequent military brushes between China and its Asian neighbours the Philippines, Vietnam, Malaysia, Brunei and Taiwan, which ring the waters believed to hold untapped oil and gas reserves.

The tensions have also alarmed the United States which has key defence treaties with many regional allies, and in a show of strength last week sent warships to patrol close to some of the reefs and islands claimed by China.

New Philippine President Rodrigo Duterte had said he was optimistic of a favourable ruling, but offered to hold conciliatory talks with China and vowed he would not "taunt or flaunt" any favourable ruling.

Referring to the UN Convention on the Law of the Sea, Manila contended the "nine-dash" line had no basis under international law and that Beijing had no "historic" claim to the waters.

South China Sea tribunal: key findings
The Hague (AFP) July 12, 2016 - A United Nations-backed tribunal on Tuesday issued a damning ruling against China on its long-running dispute with the Philippines in the South China Sea.

Here are some of the key findings in the lengthy document.

China's 'nine-dash-line' is invalid

-- The five member panel found that Chinese fishermen, amongst others, had historically made use of the islands in the South China Sea but "there was no evidence that China had historically exercised exclusive control over the waters or their resources.

"The Tribunal concluded that there was no legal basis for China to claim historic rights to resources within the sea areas falling within the 'nine-dash-line'".

Reclaimed islands have no exclusive economic zone

-- The artificial islands that China has been furiously building over recent years are not capable of sustaining a population and therefore under international treaties do not have the 200 nautical mile "exclusive economic zone" (EEZ) enjoyed by inhabited land.

"The Tribunal noted that the current presence of official personnel on many of the features is dependent on outside support and not reflective of the capacity of the features... (and) ....that none of the Spratly Islands is capable of generating extended maritime zones.

"The Tribunal found that it could -- without delimiting a boundary -- declare that certain sea areas are within the exclusive economic zone of the Philippines, because those areas are not overlapped by any possible entitlement of China."

China has behaved unlawfully

Because areas at issue are within the Philippines EEZ, Chinese construction of artificial islands and its interference with Philippine fishing and mineral activities is illegal.

"China had violated the Philippines' sovereign rights in its exclusive economic zone. The Tribunal further held that Chinese law-enforcement vessels had unlawfully created a serious risk of collision when they physically obstructed Philippine vessels."

Beijing has damaged the environment

China's large-scale land reclamation has "caused severe harm to the coral reef environment and violated its obligation to preserve and protect fragile ecosystems".

China was also remiss in failing to put a stop to the harmful "harvesting of endangered sea turtles, coral and giant clams on a substantial scale" by its fishermen.

Island building should have stopped during the dispute process

The panel said it had no jurisdiction over the military standoff at Second Thomas Shoal, where Chinese and Philippine military and law enforcement vessels are locked in confrontation.

However, "China's recent large-scale reclamation and construction of artificial islands was incompatible with the obligations on a state during dispute resolution proceedings, insofar as China has... destroyed evidence of the natural condition of features of the South China Sea that formed part of the Parties' dispute."