A House leader on Thursday eyed a congressional probe into the "gentleman's agreement" allegedly forged by former president Rodrigo Duterte with his close ally, Chinese President Xi Jinping over the hotly contested West Philippine Sea (WPS).

House Assistant Majority Leader Jefferson Khonghun said the supposed secret deal, putting the Philippines' territory and sovereignty at great risk, sparks "concern" that Congress must look into.

"The integrity of our nation's sovereignty cannot be subjected to clandestine agreements that undermine the rights of the Filipino people," said Khonghun, whose jurisdiction includes the coastal areas of the WPS.

"It is imperative that we shed light on any agreements or arrangements that could potentially compromise our country's sovereignty and territorial integrity," added the Zambales lawmaker.

The call for the probe came after Duterte's successor, President Ferdinand Marcos Jr., denounced the alleged Duterte-Xi deal, emphasizing its potential ramifications for the country's territorial integrity.

The alleged agreement is widely believed to have given China leverage to shift blame onto the Philippines amid escalating tensions in the WPS.

"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 on Wednesday.

Opposition lawmaker Edcel Lagman of Albay vehemently asserted that there can be no "gentlemen's agreement with a chronic aggressor like China" in the WPS.

"I agree with President Marcos Jr. that former President Duterte's unilateral and surreptitious agreement with China's principal official is a grave mistake and indeed compromises Philippine sovereignty," said the Liberal Party president.

"This has no binding effect," he added.

Former Cabinet members of the Duterte administration, including Duterte's ex-legal counsel and mouthpiece, Salvador Panelo, denied that they have not entered into any gentleman's agreement or whatsoever.

"I was present in the state visit made by FPRRD in China as well as in the dialogue between the Chinese President and FPRRD. No such agreement was made between the two," Panelo said.

Panelo contested that his former boss has never, and would never enter into any agreement against the country's national interest, sovereignty, and territorial integrity.

"PBBM has been misinformed or has been misled by the alleged non-existent 'gentleman’s agreement'," he claimed.

Panelo also advised the public to "be wary of spreaders of false news and bogus narratives."