China had deployed up to seven ships to Quirino Atoll, also known as Jackson Atoll, said Eugenio Bito-onon, Jr., the mayor of nearby Pagasa Island in the Spratly Islands.
The Spratlys are the most contested archipelago in the South China Sea, a resource-rich region and critical shipping lane linking North Asia to Europe, South Asia, and the Middle East.
"This is very alarming, Quirino is on our path when we travel from Palawan to Pagasa. It is halfway and we normally stop there to rest," Mr. Bito-onon told Reuters. "I feel something different. The Chinese are trying to choke us by putting an imaginary checkpoint there. It is a clear violation of our right to travel, impeding freedom of navigation."
The atoll also serves as abundant fishing grounds for local fisherman, especially now that the octopus season has started, Mr. Bito-onon said in a separate interview.
"With the Chinese ships there, our local fishermen will avoid the area so they ask where they will get their source of living if the Chinese remain in the area," he said, fearing the arrival of big Chinese clam diggers and coral harvesters.
Fishermen told the mayor, one Filipino boat had run aground in the area and was still there but was not being harassed by the Chinese vessels.
Chinese authorities did not immediately respond to faxed requests for comment from Reuters.
The Philippine military said it was trying to verify the presence of Chinese ships near Jackson Atoll, where a Chinese warship allegedly fired warning shots at Filipino fishermen in 2011.
"We know there are Chinese ships moving around the Spratly area," Spokesman Brigadier-General Restituto Padilla told Reuters. "There are also ships around Second Thomas Shoal so we want to make sure if the presence is permanent."
Second Thomas Shoal is where the Philippine Navy has been occupying and reinforcing a rusting ship that it ran aground in 1999 to bolster its claims to the disputed reef.
TENSIONS ON THE RISE
A military source from Palawan said a surveillance plane had seen four to five ships in the vicinity of Jackson Atoll last week. The source could not say if the ships were passing through or permanently stationed there because the area is close to Mischief Reef, where China is busy building an artificial island.
"There are no indications China will build structures or develop it into an island," said the source, who was not authorized to speak to the media about the South China Sea.
The Philippines Star newspaper, which earlier reported the story, quoted an unidentified fisherman as saying Chinese boats chased them away when they tried to enter the area last week.
"These gray and white Chinese ships, around four of them inside the lagoon, prevented us from entering our traditional fishing ground," he said.
Along with China and the Philippines, Brunei, Malaysia, Taiwan and Vietnam also have claims on the waters, through which about $5 trillion in trade is shipped every year.
Tensions in the region have been building recently, with the United States and others protesting against Beijing's land reclamations, along with the recent deployment of surface-to-air missiles and fighter jets in the Paracel Islands.
US Defense Secretary Ash Carter warned China on Tuesday against what he called "aggressive" actions in the region, saying there would be "specific consequences" to militarization of the South China Sea.
Beijing, for its part, has been angered by "freedom of navigation" air and sea patrols the United States has conducted near the islands it claims in the South China Sea and says it needs military facilities for its self defence.
ANOTHER DIPLOMATIC PROTEST?
So far, lodging another diplomatic protest is among the measures that the Philippines is considering in light of reports that Chinese ships have settled on another disputed area in the South China sea, the furthest incursion so far inside its exclusive economic zone (EEZ).
Department of Foreign Affairs (DFA) spokesperson Charles C. Jose said that while the agency are still verifying reports with concerned agencies, theoption will be considered to address this latest development in an already tense situation for both countries.
"We have to study carefully the next step to take if reports are true,"Mr. Jose told BusinessWorld in a text message on Wednesday afternoon. "It's [an] option that has to be studied."
Professor Jay L. Batongbacal, Director of the University of the Philippines Law Center- Institute for Maritime Affairs and Law of the Sea, said that filing diplomatic protests will no longer be enough considering the mindset of China in maintaining and increasing its foothold at the South China Sea.
The move "[indicates] a trend in China's strategy that it will stop at nothing even if there is an arbitration case against them or even if the DFA has filed diplomatic protests before," he said in a phone interview.
Besides the usual diplomatic protests, the Philippine government should also have reinforced the areas it is already holding to avoid losing more territories to the Chinese and to other claimants on areas under its economic zone, he added.
"We're not even repairing the runway at the Pagasa island while the Chinese have already finished building a new one in one of their reclaimed areas," he said.
Meanwhile, MalacaAang reiterated its position on the "primacy of the rule of law and the need for all law-abiding countries to respect the United Nations Convention on the Law of the Sea."
Presidential Communications Secretary Herminio B. Coloma Jr. said that this will be the basis for the decision of the arbitral tribunal.
The arbitration case before the international court commenced in Jan. 2013 when Manila served Beijing with a "Notification and Statement of Claim with respect to the dispute with China over the maritime jurisdiction of the Philippines in the West Philippine Sea."
The Permanent Court of Arbitration has issued its "Award on Jurisdiction and Admissibility" to the case lodged by Manila against Beijing in January 2013, following the hearings conducted in July.
A hearing on the merits of the case was held in November last year.