MANILA >> The Philippines said on Saturday it has deployed ships to a disputed area in the South China Sea, where it accused China of building “an artificial island” in an escalating maritime row.

The coast guard sent a ship “to monitor the supposed illegal activities of China, creating ‘an artificial island’,” the office of President Ferdinand Marcos Jr said in a statement, adding two other vessels were in rotational deployment in the area.

Philippine Coast Guard spokesperson Commodore Jay Tarriela told a forum there had been “small-scale reclamation” of the Sabina Shoal, which Manila calls Escoda, and that China was “the most probable actor”.

The Chinese embassy in Manila did not immediately respond to a request for comment on the Philippine assertions, which could deepen the bilateral rift.

The Philippine national security adviser called on Friday for expelling Chinese diplomats over an alleged leak of a phone conversation with a Filipino admiral about the maritime dispute.

Beijing and Manila have been embroiled for a year in heated stand-offs over their competing claims in the South China Sea, where $3 trillion worth of trade passes annually.

China claims almost all of the vital waterway, including parts claimed by the Philippines, Brunei, Malaysia, Taiwan and Vietnam. The Permanent Court of Arbitration ruled in 2016 that Beijing’s claims had no basis under international law.

China has carried out extensive land reclamation on some islands in the South China Sea, building air force and other military facilities, causing concern in Washington and around the region.

A Philippine vessel has been anchored at the Sabina Shoal to “catch and document the dumping of crushed corals over the sandbars”, Tarriela said, citing the “alarming” presence of dozens of Chinese ships, including research and navy vessels.

Tarriela said the presence of Chinese vessels at the atoll 124 miles (200 km) from the Philippine province of Palawan coincided with the coast guard’s discovery of piles of dead and crushed coral.

The coast guard will take marine scientists to the areas to determine whether the coral piles were a natural occurrence or caused by human intervention, he said.

He added it intends to have a “prolonged presence” at Sabina Shoal, a rendezvous point for Philippine vessels carrying out resupply missions to Filipino troops stationed on a grounded warship at the Second Thomas Shoal, where Manila and China have had frequent maritime run-ins.