New Philippine President Rodrigo Duterte said Thursday he would not "taunt or flaunt" a favourable ruling in a highly sensitive legal challenge against Beijing over a South China Sea dispute.

But it was unclear whether Duterte intended to telegraph his soft diplomatic punches, with his comments made during his first cabinet meeting that was broadcast live on national television before being cut abruptly during the discussions on China.

After discussions on climate change, cutting red tape and airport congestion, the meeting turned to an imminent ruling by a UN-backed tribunal on a case filed by the Philippines' previous government against Beijing over competing claims to the South China Sea.

In comments that are likely to please Beijing, Duterte issued instructions not to "taunt or flaunt" a verdict in favour of the Philippines.

Foreign Affairs Secretary, Perfecto Yasay, then revealed some foreign governments had been urging the Philippines to "make stronger statements".

"I am averse to that idea and I told them in no unmistakable terms," Yasay said.

Yasay did not name the governments that had been pushing for stronger statements, but described them as "those who are concerned about ensuring freedom of navigation".

The United States has been one of the most vocal nations calling for China to ensure "freedom of navigation" in the South China Sea.

Yasay then started discussing what the Philippines should do if China "will dig in and put us to the test" but then abruptly stopped.

Almost immediately afterwards the broadcast, which was distributed by the state broadcaster and carried live on commercial networks as well as Internet portals for about 40 minutes, was also cut.

The cabinet meeting took place a few hours after Duterte was sworn in as the Philippines' president for a six-year term.

He took over from Benigno Aquino, who put the Philippines' long-running dispute with China at the top of his foreign policy agenda, publicly drawing comparisons between Beijing's expansionist efforts in the sea and Nazi Germany's take over of parts of Europe.

Aquino also launched the legal action with the UN-backed tribunal in The Hague, arguing that China's claims to most of the strategically vital and resource-rich sea were in violation of international law.

China's claims extend close to the Philippines' coast, as well as those of other Southeast Asian countries.

The tribunal is set to issue a verdict on July 12.

Infuriated by Aquino's strategy, China has vowed to ignore the tribunal's ruling and repeatedly expressed hopes of better ties with the Philippines under Duterte.

Duterte's media aides were not immediately available to comment over whether the discussion on China was meant to be televised.