Supreme Court Associate Justice Antonio Carpio said on Thursday President Rodrigo Duterte should disclose the deal he has with China concerning the Benham Rise.

In an interview with reporters in Makati City, Carpio, who helped the Philippines on its arbitral case against China on the South China Sea, said it is better to find out first the "agreement," which Duterte earlier mentioned when asked about the presence of Chinese vessels in Benham Rise during the past months.

He said it is difficult to know the consequences of China's action "unless we know the nature of the agreement."

The United Nations Commission on the Limits of the Continental Shelf confirmed in 2012 the Philippine claim over Benham Rise to be part of its continental shelf.

Carpio explained that under the United Nations Convention on the Law of the Sea, the Philippines has the exclusive right in those areas within the 200 nautical miles exclusive economic zone. It has the right over all the natural resources,the fish, oil, gas and other mineral resources.

But since Benham Rise, which is within the 150 nautical miles extended continental shelf of the Philippines, Manila has only the exclusive right to the oil, gas and minerals, but not to the fish, Carpio said.

Thus, if China is doing a research on the water column or on the fish in Benham Rise, it is not a violation of the Philippines' rights over the area because the research is for "humankind."

But if Beijing has been doing exploration on oil, gas and minerals, "they can't do that. It's only the Philippines which can explore," he said.

Duterte, in a press conference on Monday, said China did not commit any incursion on Benham Rise as the he was advised about it and there was an agreement on that.

But Defense Secretary Delfin Lorenzana, prior to Duterte's press conference, raised concern on the presence of Chinese vessels presence in Benham Rise.

Acting Foreign Affairs Secretary Enrique Manalo, in a press conference on Thursday, said he was not aware of any agreement with China regarding Benham Rise.

But he said any research in the area should have the permission of the Philippine government. Celerina Monte/DMS