This photo was taken during a marine expedition at Benham Rise last May 26, 2016. Branching corals contribute to the complexity of the reef. Oceana Philippines

MANILA- Acting Foreign Affairs Chief Enrique Manalo refused to comment on President Rodrigo Duterte's statement that he had agreed to allow Chinese research ships in Benham Rise, a large and resource-rich area east of Luzon.

Speaking to reporters on Thursday, Manalo said he was not in a position to confirm or deny Duterte's statement, and instead took note of China's statement re-affirming the Philippines' sovereign rights over Benham Rise.

"They (China) had acknowledged and in fact, even said very clearly that the Philippines has sovereign rights over Benham Rise," Manalo said.

He added that his department had sent a note verbale to China regarding Benham Rise, which Beijing acknowledged and responded with a re-affirmation of the Philippines' sovereign rights.

"They just re-affirmed that the Philippines has sovereign rights over Benham Rise," Manalo said.

Manalo said he only read about the supposed research agreement in newspapers, and explained that President Duterte had called for increased patrols in Benham Rise.

"The President was quite clear when he told us that we need to increase patrols on Benham Rise," Manalo said.

Asked whether the Foreign Affairs department has received any reports of Chinese surveying activities along Benham Rise, Manalo said they have not received, any and insisted that the Philippines' claim has been clearly defined by the United Nations Convention on the Law of the Sea (UNCLOS).

"We have no policy on that (research project). And of course there are ships passing through the area exercising freedom of navigation. The fact that this is within the sovereign rights and jurisdiction of Philippines, any ship would have to get permission from the Philippines if they wish to undertake any research," Manalo said.

Manila's claim to Benham Rise, a 13-million-hectare continental shelf located east of Luzon island believed to be gas-rich, was approved by the United Nations in 2012.

Chinese foreign ministry spokesperson Hua Chunying said China “fully respects the Philippines' rights over the continental shelf in the Benham Rise, and there is no such thing of China challenging those rights.”

Defense Secretary Delfin Lorenzana, who broke the news on the Chinese ships' presence, was surprised by Duterte’s comments as he was not aware of any agreement between the Philippines and China involving Benham Rise.

Lorenzana last week said Chinese survey ships were spotted in Benham Rise, a 13-million hectare, bio-diverse undersea region.

Manalo, however, reiterated that the right of innocent passage is allowed and that the Philippines is not questioning this right.

"It is in our interest and duty to ensure that other countries observe those rights as stated in UNCLOS. There is a right of innocent passage so we are not questioning that," Manalo said.