The Philippines has sent two new diplomatic protests to China over its failure to withdraw what it called on Friday "threatening" vessels that were massing in contested areas of the South China Sea.
The Philippines has ramped up its rhetoric in recent weeks over the lingering presence of hundreds of Chinese boats in its 200-mile Exclusive Economic Zone (EEZ), testing relations between two countries that have sought to heal their historic rifts.
The Philippine foreign ministry said maritime officials had observed the "continued unauthorised presence and activities" of 160 Chinese fishing and militia vessels around the disputed Spratly islands and Scarborough shoal, as of April 20.
Five Chinese coastguard vessels were also spotted around the areas.
"The continued swarming and threatening presence of the Chinese vessels creates an atmosphere of instability and is a blatant disregard of the commitments by China to promote peace and stability in the region," the foreign ministry said.
It comes as the Philippines announces a boosting of its presence of vessels in its EEZ. Under international law, foreign vessels are permitted to make "innocent passage" through a country's EEZ.
Chinese diplomats have denied that militia were aboard the vessels.
China's embassy in Manila did not immediately respond to a request for comment on Friday on the new protests.
China claims almost the entire South China Sea, where about $3 trillion worth of ship-borne trade passes each year. An international arbitral tribunal in 2016 invalidated China's expansive claim, which is based on its own maps.
Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have competing claims to various islands and features.
Philippine President Rodrigo Duterte said on Monday he was prepared to deploy navy ships to assert the country's sovereign rights to oil and mineral resources in its EEZ, telling China that if it started drilling for oil, so will he.