The Philippines on Monday warned China that it would file more diplomatic protests for every delay in the withdrawal of its vessels from a disputed reef in the South China Sea.

The Department of Foreign Affairs, in a statement, demanded that China should immediately withdraw the fishing vessels and maritime assets from the area of Whitsun Reef, known in the Philippines as Julian Felipe Reef, and also rejected China's description of the area as its "traditional fishing grounds."

"Julian Felipe Reef is part of the Kalayaan Island Group and lies in the Exclusive Economic Zone of the Republic of the Philippines," the department said, while pointing out the land feature's geographical proximity to the country.

Photo taken March 7, 2021 shows Chinese fishing boats in the South China Sea. (Photo courtesy of the Philippine government)(Kyodo)

It said the current situation should be handled in accordance with the U.N. Convention on the Law of the Sea and a 2016 ruling of the Permanent Court of Arbitration that invalidated China's historical claim over much of the South China Sea.

The court "further ruled that UNCLOS superseded any historic rights, or other sovereign rights or jurisdiction in excess of the limits imposed therein," it noted.

China continues to disregard the ruling issued in The Hague and did not participate in the arbitration proceedings.

On Saturday, Philippine Defense Secretary Delfin Lorenzana said that there were still 44 Chinese vessels at the disputed reef, down from several hundred, as assessed by maritime and aerial surveillance."

"The Chinese Ambassador Huang Xilian has a lot of explaining to do...I am no fool. The weather has been good so far, so they have no reason to stay there," Lorenzana said in a statement.

China had said rough sea conditions caused the vessels to be moored in the vicinity of the reef, which it calls Niu'e Jiao and insists are part of the Spratly Islands which it claims.

The Chinese Embassy responded to Lorenzana's remarks later Saturday by saying Philippine authorities should "avoid any unprofessional remarks which may further fan irrational emotions."

"The Chinese fishermen have been fishing in the waters for their livelihood every year. It is completely normal for Chinese fishing vessels to fish in the waters and take shelter near the reef during rough sea conditions. Nobody has the right to make wanton remarks on such activities," it said.

On Sunday, Lorenzana fired back by demanding that China "refrain from conducting activities that disturb regional and international peace and security."

"The continued presence of Chinese maritime militias in the area reveals their intent to further occupy features in the West Philippine Sea," he said, using a local name for the South China Sea waters within the country's 200-nautical-mile exclusive economic zone.

He said China had used similar tactics before to occupy Scarborough Shoal and Mischief Reef, "brazenly violating Philippine sovereignty and sovereign rights under international law."

Also Sunday, Philippine Foreign Affairs Secretary Teodoro Locsin said he was "considering a demarche" or a political step, despite his initial diplomatic protest filed last March 21.

Meanwhile, the United States, Japan, Australia, Britain and Canada have joined in criticizing China's continuing encroachments in the South China Sea.

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