BANGKOK, Thailand - The Philippines has requested China to clarify reports that it plans to build the first permanent structure on the disputed Panatag (Scarborough) shoal in the South China Sea, a Cabinet official said Wednesday.

"Ang masasabi ko lang ngayon is that we have already approached China to seek clarification on this report and plan," acting Foreign Affairs Secretary Enrique Manalo said in a press conference.

Manila "will have to wait for China's reply" before filing a possible protest against Beijing over its purported plan to build an environmental monitoring station on Panatag, Manalo added.

"In the meantime the Philippine government is maintaining a regular and close watch over Scarborough shoal," he said.

DFA Spokesperson Charles Jose said the agency has sent China a note verbale for clarification. If the report is confirmed to be true, Jose said the Philippines "will definitely file a protest note against China for this planned action."

China 5 years ago started blockading Panatag, a rocky outcrop within the Philippines' 200 mile exclusive economic zone (EEZ).

Until late last year, Beijing had 2 to 3 coastguard ships guarding the shoal and stopping Filipinos from tapping its vast fish stocks. An international tribunal ruled last year that Beijing violated Manila's entitlements and no country has sole rights to fish there.

However, just days after Duterte visited China and heralded a new era of ties, Filipinos returned to fish at the periphery of the shoal, unimpeded by Chinese vessels.

But a recent report by Chinese newspaper Hainan Daily quoted Sansha Communist Party secretary Xiao Jie as saying that preparations were underway to build a monitoring station in the shoal.

AGUIRRE BARES LOOMING PROTEST

Justice Secretary Vitaliano Aguirre told reporters on Tuesday that Manila would file a complaint against Beijing's reported aggressive action.

"The case which will be filed is fairly strong I think," he said.

Aguirre also said the Philippines would renew its strong ties with Washington in the face of China's plan.

"As a matter of fact, we're strengthening the relationship with the United States," he told reporters.

President Rodrigo Duterte meanwhile was asked on Sunday for his response to the report of a radar station to be built at the Scarborough Shoal.

"We cannot stop China," he said, noting it is pointless to go to war against Beijing.

DUTERTE FIRM ON PH CLAIM: CAYETANO

The President however "will not give up a square centimeter of Philippine territory," Senator Alan Peter Cayetano said.

Cayetano said Duterte is "working quietly" on long-term strategies to assert Manila's rights to the waterway.

He did not elaborate on the strategy but instead asked members of the media to "give a little bit of latitude to DFA and other departments."

"Because although we have to report to the people, what country will be able to achieve its objectives if we announce our strategy while we are implementing our strategy," he said.

Last month, former Foreign Minister Perfecto Yasay said the US had dissuaded China from reclaiming Scarborough Shoal, which security analysts consider a red line that could escalate tension in the region.

China has put missiles and radar on some of its seven man-made islands in another part of the South China Sea, a strategic water claimed by Brunei, Malaysia, the Philippines, Taiwan and Vietnam.

The US stresses the importance of free navigation in the sea, through which more than $5 trillion worth of trade passes each year. -- With Reuters