“The Chinese will not occupy new features in the South China Sea nor are they going to build structures in Scarborough Shoal,” Lorenzana told lawmakers late on Monday, referring to a prime fishing ground close to the Philippines that China blockaded from 2012 to 2016.

China claims almost the entire South China Sea, a waterway through which about US$3 trillion worth of seaborne trade passes every year. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have conflicting claims in the area.

Asked about the Philippine comments, Chinese Foreign Ministry spokeswoman Hua Chunying said that China had sovereignty over the Spratly Islands and their nearby waters, and would continue to dedicate itself to peacefully resolving the dispute through talks with the parties directly involved.

Philippine President Rodrigo Duterte, who took office in June last year, has courted China and avoided rows over maritime sovereignty that dogged his predecessors, while berating traditional ally the United States over several issues.

China has built seven islands on reefs in disputed areas, three of which, experts said, are capable of accommodating fighter jets. They have runways, radars and surface-to-air missiles which China said are for defence.

Lorenzana did not comment when lawmakers, citing reports from the military, told him that five Chinese ships had shown up almost 5km off the Philippine-held Thitu Island in the Spratly archipelago on Saturday.

The military’s public affairs chief, Colonel Edgard Arevalo, declined to comment until the armed forces had the “whole picture on the current situation”.

Cayetano assured lawmakers on Tuesday that any energy deal with China would not violate the constitution and would conform to a 60-40 per cent revenue sharing, weighted towards the Philippines.

“We can come up with a commercial deal that is better than Malampaya in the disputed areas,” Cayetano said, referring to an existing natural gas project off Palawan island between the government and Chevron, a resource which is expected to be depleted by 2024.

“How can any Filipino argue with that? ... It cannot violate the constitution.”

But such an arrangement could be complex and sensitive as both countries claim the oil and gas reserves. Sharing them could be construed as legitimising the other’s claim, or even ceding sovereignty.

The Permanent Court of Arbitration in The Hague invalidated China’s claim over most of the South China Sea in July last year. China has refused to recognise the ruling, which clarified Philippine sovereign rights to energy reserves within its Exclusive Economic Zone (EEZ).

The Philippine energy department last month said it might resume drilling for oil and gas on the Reed Bank, which is within the zone, before the end of the year, offering new blocks to investors in a bidding in December.

The Philippines suspended exploration in the Reed Bank in late 2014 as it pursued the international arbitration.

Minority lawmakers Gary Alejano and Edcel Lagman opposed the plan for an energy deal saying it would be illegal.

“This is contrary to our constitution because these areas should be exclusively for Filipinos,” Lagman said.

Cayetano declined to give details of the talks and requested an executive session of congress to divulge information about the venture with a Chinese energy company, which he did not identify.

Manuel Pangilinan, chairman of Philippine oil and gas firm PXP Energy Corp, said this month that any joint venture is likely to be with “a company like CNOOC”, referring to the China National Offshore Oil Corp.

Officials from the foreign and energy ministries have said privately that any deal would likely be commercial only and both sides would keep the issue of sovereignty out of the equation to avoid complications.