MANILA - Two opposition senators on Wednesday disagreed with a supposed joint exploration in the West Philippine Sea with China.

Foreign Affairs Secretary Alan Peter Cayetano said Tuesday the Duterte administration was working on a framework for possible oil exploration with Beijing where companies can work on a commercial level without damaging the country’s claims.

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"It is preposterous and treacherous. It reverses our historic victory at The Hague and signs away Philippine sovereignty in the West Philippine Sea," Senator Risa Hontiveros said in a statement.

She said the plan of the Department of Foreign affairs was "absurd" because it recognized China's "claim and ownership" over the West Philippine Sea.

"In case the DFA failed to read the ruling, the UN decision is very clear. We have sovereign rights to access offshore oil and gas fields, including the Reed Bank, within our 200 mile Exclusive Economic Zone. We don't share ownership of the West Philippine Sea with China," she said.

Senator Bam Aquino meanwhile underscored that a "treaty" is needed before any such exploration.

He also called on his colleagues to push through with the hearing of the committee on foreign affairs next Monday to tackle Manila's relationship with Beijing.

"Kailangang matuloy yan para malaman natin sa iba't ibang mga larangan kung ano ba talaga yung mga deals natin sa China? Ano ba ang mga deals natin pagdating sa teritoryo? Ano ang deals natin sa ekonomiya? Ano ba ang deals natin sa exploration? Hindi malinaw at hindi transparent," he said in an interview with ABS-CBN News.

"Kailangan maging malinaw yan sa Senado at kaming mga senador at taongbayan ang maghuhusga kung itong deals natin sa kanila ay lamang tayo o dehado tayo dito," he said.

Cayetano on Tuesday said the government of President Rodrigo Duterte has been transparent in handling issues concerning the West Philippine Sea, and that there were no secret meetings or deals with Chinese officials.

He said the administration has offered briefings to Congress and Acting Chief Justice Antonio Carpio, who was part of the team that argued for Manila before the arbitration court in its petition against China over maritime rites in the South China Sea.

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The framework on the joint exploration will not go beyond the Philippine Constitution and follow as a standard the Malampaya 60-40 sharing of revenues for the Philippines," said Cayetano.

He said the Chinese “seems amenable” to it and that both sides have exchanged principles but not the draft yet, which he expects to be finished by this month or next.

He said the draft will undergo review and experts on international, Constitutional law and oil gas will be consulted and that the country will make sure it passes the scrutiny of the Supreme Court. - with a report by Willard Cheng, ABS-CBN News