MANILA— Former Foreign Affairs Secretary Albert del Rosario on Thursday said it was a "national tragedy" that President Rodrigo Duterte considers the 2016 arbitral ruling that invalidated China's excessive claims in the South China Sea a mere scrap of paper.

In a statement, Del Rosario said the country's allies such as the United States, Australia, Japan, and the United Kingdom, among others, believe that the ruling by a United Nations-backed tribunal is "valid, binding and should be enforced against China pursuant to international law."

The arbitration court had ruled in favor of Manila and junked Beijing's claim to about 90 percent of the South China Sea, within which is the smaller West Philippine Sea — the country's exclusive economic zone in the resource-rich waters.

Del Rosario was the Philippines' top diplomat when it hailed China to court. The ruling came out shortly after Duterte became President. He has since pursued friendlier ties with China despite recurring incursions in the West Philippine Sea.

• READ: Duterte wrong to blame Del Rosario for China's seizure of Scarborough Shoal, says UP prof

"China, the illegal occupant in the West Philippine Sea, believes that the Arbitral Ruling is a mere scrap of paper. The Philippines is the country which won the Arbitral Ruling against China," said Del Rosario.

"It is, therefore, a national tragedy that the President of the Philippines takes the side of China and believes that the Arbitral Ruling is a scrap of paper meant to be thrown in the waste basket, to the severe prejudice of the Filipino people," he added.

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President Rodrigo Duterte on Wednesday night likened the country's victory as "just a piece of paper" that belonged to the "wastebasket."

"Actually sa usapang bugoy, sabihin ko sa ‘yo, bigay mo sa akin, sabihin ko, ‘P***** *** papel lang ‘yan, itatapon ko ‘yan sa wastebasket,'" the chief executive said in his taped address.

(Actually, if you give that to me, I will tell you, 'Son of *****, I will throw that in the wastebasket.')

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Because of this, the country's former top diplomat reminded Duterte that it is his sworn duty under the Charter as chief executive to protect the country's territory, most especially the West Philippine Sea, and "enforce" the Arbitral Award that China continues to disregard.

"With due respect, this is not a blaming game among Filipinos, but a constitutional mandate to be acted upon against a foreign aggressor for the benefit of our country and the Filipino people," he explained.

He also questioned the reason why Duterte is blaming Filipinos for the loss of the Scarborough Shoal, instead of China.

Duterte has repeatedly blamed his predecessor Benigno Aquino, Jr. for the supposed absence of Philippine ships in the waterway, which paved the way for Beijing to occupy the area, in reference to a 2012 standoff.

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"[W]e wish to reiterate that it was China which deceitfully breached the US-brokered agreement for a mutual withdrawal. Until now, China continues to openly violate the sovereignty and territorial integrity of the Philippines by illegally occupying certain features in the West Philippine Sea," according to Del Rosario.

LORENZANA: WE DEFEND WHAT IS RIGHTFULLY OURS

In a statement, Defense Secretary Delfin Lorenzana said while it is true that no international law enforcement body could enforce the ruling, the country would still continue defending the West Philippine Sea.

"What President Duterte said last night regarding the PCA ruling is correct... However, even without the PCA ruling, we will continue to defend what is rightfully ours," the statement read.

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He said the Philippines will continue defending its territories without the need to go to war and while maintaining peace and stability in the disputed waters.

Maritime drills in the West Philippine Sea and the Kalayaan Islands will also push through.

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China's Foreign Ministry earlier urged Philippine authorities to stop its maritime drills there, most especially in the Scarborough Shoal, or what they call Huangyan Island, as these areas are supposedly "under China's jurisdiction."

The Philippine Coast Guard and Bureau of Fisheries and Aquatic Resources have been holding maritime drills in the West Philippine Sea since late April, even as Chinese ships have been sighted there since early March.

The deployment of additional vessels and aircraft in the area aims to intensify operations against illegal, unreported, and unregulated fishing and to "increase safety of life at sea operations," the NTF-WPS earlier said.

Around 200 ships, meanwhile, are still moored in the West Philippine Sea, a geospatial intelligence firm said earlier in the day.

• About 200 ships still moored at West Philippine Sea, geo-analyst says

The Philippine government has filed several protests regarding the continued incursions of Chinese ships in the country's EEZ.