Hong Kong (CNN) -- The Philippines said Wednesday that its largest naval vessel is engaged in a standoff with two Chinese maritime surveillance ships in a remote lagoon in the South China Sea.
The Philippine Department of Foreign Affairs said the country's navy had sent the BRP Gregorio del Pilar, a 378-foot cutter, to the area of Scarborough Shoal on Sunday after surveillance aircraft spotted eight Chinese fishing boats anchored inside the lagoon.
China and the Philippines both claim that Scarborough Shoal, about 200 kilometers west of the Philippine mainland, is "an integral part" of their territory.
A boarding team from the Gregorio del Pilar went to inspect the Chinese fishing boats Tuesday morning and found "large amounts of illegally collected corals, giant clams and live sharks" inside one of the boats, the Department of Foreign Affairs said in a statement.
Later Tuesday, the Gregorio del Pilar reported that the two Chinese surveillance ships had arrived and taken up a position at the mouth of the lagoon, blocking the way to the fishing boats and "preventing the arrest" of the fishermen. The situation remained the same Wednesday morning, the Philippine statement said.
The Philippine foreign minister, Albert Del Rosario, is seeking a "diplomatic solution" to the situation with China, the statement said.
The Chinese Embassy in Manila has complained to the Philippine authorities about "the harassment of Chinese fishermen," China's official news agency reported Wednesday.
China has "urged the Philippine side to stop immediately their illegal activities and leave the area," Xinhua reported, saying that the fishermen were taking shelter in the lagoon "due to harsh weather conditions."
The embassy is "still engaged in discussions with the Philippine Department of Foreign Affairs to seek a solution" and maintain peace and stability in the South China Sea, Xinhua said.
The South China Sea -- a 1.3 million square mile patch of the Pacific Ocean bracketed by China and several Southeast Asian nations -- is dotted with hundreds of largely uninhabited islands and coral atolls that are home to some of the world's most diverse marine life. Also under its waves lie potentially huge reserves of natural gas and oil.
That prospect has peppered the sea with competing claims from China, Vietnam, the Philippines, Malaysia, Brunei and Taiwan. It has also resulted in frequent small-scale clashes. Last year, a spate of incidents took place between Chinese and Vietnamese vessels.
CNN's Jethro Mullen and Brian Walker contributed to this report.