MANILA, Philippines - Philippine President Rodrigo Duterte stopped construction work on a newly formed sandbar in the disputed South China Sea after China protested, the defence chief said Wednesday, disclosing details of the new territorial spat for the first time.

The dispute over a string of sandbars called Sandy Cay emerged in August and prompted China and the Philippines to consider negotiating some sort of protocol or arrangement to allow both sides to prevent such incidents from spiraling out of control, Lorenzana said.

The rift over the tiny sandbar near the Philippine-occupied Thitu island in the Spratlys archipelago remains unresolved but both sides pledged not to occupy any new territory, he said.

China's claims to most of the South China Sea overlap with those by the Philippines and four other governments. Despite that, tensions have eased since Duterte took over as president last year and took steps to thaw once-frosty relations Beijing.

Duterte has courted Chinese trade and assistance and taken a nonconfrontational approach to their territorial disputes. He has refused to immediately take up with China a ruling by a U.N.-linked tribunal that invalidated Beijing's sprawling claims in the South China Sea, sparking criticism from nationalists and left-wing groups that wanted him to demand Chinese compliance with the landmark decision immediately.

"We tried to put some structures in one of the sandbars near our island and the Chinese reacted," Lorenzana told a diplomatic forum in Manila, adding that Duterte later ordered, "Let's pull out."

Duterte made the decision after Foreign Secretary Alan Peter Cayetano advised him of an agreement involving China and the Philippines for a halt on new construction in the disputed waters, Lorenzana later told a news conference. Philippine foreign affairs and military officials refused to divulge details of the dispute at Sandy Cay in August.

Two senior Philippine security officials told The Associated Press at the time that three Chinese navy ships, a coast guard vessel and 10 fishing boats began keeping watch on Sandy Cay after spotting the Filipinos on the barren sandbar.

A government security report seen by the AP in August said three Chinese navy ships, a Chinese coast guard ship and 10 Chinese fishing vessels took positions off Sandy Cay. Its nearest sandbar is about 2.5 nautical miles (4.6 kilometres) from Philippine-occupied Thitu Island.

On Aug. 15, a blue Chinese helicopter flew low off Thitu's southwest coast, the report said.

Philippine troops and villagers based at Thitu call it Pag-asa - Tagalog for hope - while the Chinese call the island Zhongye Dao.

The Chinese military presence off Sandy Cay near Thitu sparked concerns in Manila.

Philippine Supreme Court Senior Associate Justice Antonio Carpio, who has studied the disputes extensively, said then that the Chinese navy ships and other vessels encroached in the Philippine island's 12-nautical mile (22-kilometre) territorial waters.

"In short, Sandy Cay is a Philippine land territory that is being seized, to put it mildly, or being invaded, to put it frankly, by China," Carpio said in a statement.

The long-unresolved disputes are expected to be among the issues that would get the spotlight in an annual summit of Southeast Asian nations and their Asian and Western counterparts in Manila next week. Lorenzana welcomed progress in efforts by the Association of Southeast Asian Nations, which includes four claimant countries in the South China Sea, and China to negotiate a so-called code of conduct to prevent armed conflicts from erupting in the strategic waters.