File photo from August 2022 shows Philippine Coast Guard personnel carrying debris, which the Philippine Space Agency said has markings of the Long March 5B Chinese rocket that was launched on July 24, in waters off Mamburao, Occidental Mindoro province, Philippines. – AP

MANILA (The Straits Times/Asia News Network): Residents of the Philippines-occupied Thitu Island, part of the disputed Spratlys archipelago in the South China Sea, said they heard blasts after a maritime encounter between the Philippine Navy and the China Coast Guard.

The Philippine Daily Inquirer reported that police believe the loud blasts, heard between 11.30am and 3pm on Sunday (Nov 20), allegedly came from “artillery guns/weapons” from the nearby Subi Reef, one of the biggest artificial islands built by Beijing in the Spratlys. Military officials are verifying the source of the blasts.

The explosions were heard a few hours after a Chinese Coast Guard vessel blocked a Philippine naval boat and “forcefully” took suspected rocket debris found floating off the coast of Thitu Island, the Philippine military said on Monday.

Vice-Admiral Alberto Carlos, commander of the Philippine military’s Western Command, said the Naval Station Emilio Liwanag (NSEL) sent a team to retrieve the metallic object that was found drifting towards a nearby sand bar at around 6.45am.

He added that the team tied the object to its boat and began moving towards the shore. But a Chinese Coast Guard vessel with bow number 5203 blocked the boat twice before deploying its rigid hull inflatable boat.

“The said Chinese Coast Guard inflatable boat forcefully retrieved said floating object by cutting the towing line attached to the NSEL rubber boat. The rigid hull inflatable boat then towed it back to the Chinese Coast Guard vessel,” he said.

The NSEL team returned to base unharmed.

The incidents occurred two days before United States Vice-President Kamala Harris is set to visit on Tuesday the island province of Palawan, the biggest Philippine island adjacent to the Spratlys. Brunei, Malaysia, Taiwan and Vietnam also claim parts of the area.

She is expected to shore up ties with one of the US’ oldest allies in Asia, amid rising tension with Beijing over the South China Sea dispute and Taiwan.

She is expected to be welcomed aboard the BRP Teresa Magbanua, a new vessel from Japan that has been patrolling parts of the Philippines’ exclusive economic zone in the South China Sea that Beijing is claiming as its own.

The Chinese Embassy in Manila did not immediately respond to a request for comment from The Straits Times.

Harris arrived in Manila on Sunday evening and will hold a series of engagements on Monday, including meetings with Philippine President Ferdinand Marcos Jr and Vice-President Sara Duterte.

An international tribunal struck down Beijing’s sweeping claims in the South China Sea in 2016 and ruled that the West Philippine Sea, where Palawan is located, belongs to Manila.

China does not recognise the ruling but Washington has vowed to defend its military ally if the Philippines’ forces are attacked in the South China Sea, a conduit for about US$3 trillion (S$4.1 trillion) worth of shipborne trade each year.