SPEAKER Martin Romualdez said on Monday the House of Representatives would go ahead with its investigation on the alleged "gentleman's agreement" concerning the West Philippine Sea (WPS).

Romualdez said in his speech as the House session resumed that he "will direct the appropriate House committees to conduct an inquiry, in aid of legislation, to determine the adverse impact of such agreement on our national interests, particularly our sovereignty, sovereign rights, and territorial integrity."

Former president Rodrigo Duterte has admitted he had an agreement with Chinese President Xi Jinping to keep the status quo in the West Philippine Sea to ease tensions created by their countries' overlapping claims.

The agreement involved banning the transport of maintenance or repair materials for the BRP Sierra Madre on Ayungin Shoal, which serves as a remote outpost for Philippine troops.

"Ayungin Shoal is part of the country's exclusive economic zone (EEZ) as reaffirmed by the 2016 arbitral ruling on the South China Sea arbitration case," Romualdez said.

He said that under Article 56 of the United Nations Convention on the Law of the Sea, "the coastal state, which in this case is clearly the Philippines, has the right to build and maintain structures within its [EEZ]."