President Ferdinand Marcos Jr. on Wednesday said he is horrified by the alleged 'gentleman’s agreement' between former President Rodrigo Duterte and Chinese President Xi Jinping on the West Philippine Sea row.

Marcos addressed the issue for the first time after former Presidential Spokesperson Harry Roque disclosed that Duterte and Xi had agreed to keep the status quo at the Ayungin Shoal, where BRP Sierra Madre is located.

"I am horrified by the idea that we have compromised, through a secret agreement, the territory, the sovereignty, and the sovereign rights of the Filipinos," Marcos said in a media interview.

"If this agreement implies that we need permission from other countries to act within our territory, it would be difficult to adhere to such an agreement," Marcos added.

Marcos also mentioned that he has summoned Chinese ambassador Huang Xilian to shed light on the supposed agreement since there were no records regarding the topic on the Philippines' end.

"I'll ask him to explain who you were talking to? Who was really involved? What did you discuss? What did you agree upon? Was this an official matter or a personal one? What is this about? Because we have no records," Marcos said.

"There's no record anywhere. So all of this was done secretly. Why did they do it? If they were going to do it, why make it secret? It's quite puzzling. So, it's not a good situation," Marcos added.

He said that the Duterte administration did not brief him regarding the purported agreement, adding that he has yet to get a clear answer from the former officials of his predecessor.

To recall, former Presidential Legal Counsel Atty. Salvador Panelo contradicted Roque's claim on the WPS, saying that Marcos' predecessor has already denied entering into such an agreement with China.

“We don’t know anything about it; there is no documentation, there is no record. We were not briefed. When I came into office, nobody told me that there was such (an) agreement,” Marcos said.

"We're speaking to his former officials. Maybe not (the former president) himself, but we're asking all his former officials, 'What's this about? Please explain it to us so we understand what's going on.' We still haven't received a clear answer," Marcos added.

China asserts sovereignty over nearly the entire South China Sea, which overlaps with territorial claims made by the Philippines, Vietnam, Malaysia, and Brunei.

In 2016, the Permanent Court of Arbitration in The Hague ruled that China's claims lacked legal validity, a decision that Beijing has refused to accept.