Former Solicitor General Florin Hilbay on Monday warned that the administration's plan to conduct a joint exploration with the government of China may lead to a waiver of the arbitration case won by the Philippines two years ago.

"It will waive the whole decision on the Philippine vs. China (case). We cannot say that the West Philippine Sea is ours," Hilbay told the Daily Manila Shimbun in an interview.

"The moment they entered to a joint development, they recognized again China's right that you already removed after we win in the decision," said Hilbay, who is running for senator in the 2019 elections.

The joint exploration deal is expected to be signed during Chinese President Xi Jinping's visit to the country on November 20 and 21.

He noted President Rodrigo Duterte's statement saying the Philippines belongs to the Filipino people will be "useless" if the contract on the joint exploration will recognize China's rights on the West Philippine Sea.

In a forum in Quezon City, Hilbay said the administration's strategy in dealing with the Chinese government is setting aside territorial disputes.

"It is not possible to set aside because there is nothing to set aside. Our maritime spaces is contested so you can't say you will suspend the decision," he explained.

He said once the decision was waived because of the joint exploration, they can't take it back.

"The legal consequences is you (administration) give the decision away that results to unequivocal waiver," he said.

Looking at the strategic perspective, Hilbay said the "economic gains of China in the joint exploration is nothing compare to the waiver of the decision".

The Hague-based Permanent Court of Arbitration in 2016 ruled in favor of the Philippines, which questioned China's sovereign and historic claim in almost the entire South China Sea through its nine-dash line, including those areas within the 200 nautical miles exclusive economic zone of the Philippines. Ella Dionisio/DMS