The Philippines has sent a second ship to a stand-off with two Chinese vessels in the South China Sea, even as both sides pledged diplomacy.
A coast guard boat will join the country's largest warship at the Scarborough Shoal, navy commander Vice-Admiral Alexander Pama said.
A foreign affairs spokesman said the Philippines would continue negotiations with China.
Both claim ownership of the shoal off the Philippines' north-western coast.
The warship found eight Chinese fishing vessels at the shoal when it was patrolling the area on Sunday, the Philippines said.
Raul Hernandez of the Philippines' foreign affairs department told reporters: "What is important is that we are talking to them to reach a diplomatic solution. The diplomatic solution should be fair and workable."
He said the coast guard vessel had arrived in the area, saying: "It is there to support our navy and to show our flag."
Differing views
In a statement, the Philippines said that its navy boarded the ship and found a large amount of illegally-caught fish and coral.
Two Chinese surveillance ships then apparently arrived in the area on Tuesday, placing themselves between the warship and the fishing vessels, preventing the navy from making arrests.
The Philippines summoned Chinese ambassador Ma Keqing on Wednesday to lodge a protest over the incident. However, China maintained it had sovereign rights over the area and asked that the Philippine ship leave the waters.
China's state-run newspaper China Daily claimed in an editorial that the Chinese fishermen were "harassed" by the Philippine naval boat.
"China should take more measures to safeguard its maritime territory," the newspaper stated.
"The latest moves by China's two neighbours are beyond tolerance," it added, referring to Vietnam. "They are blatant challenges to China's territorial integrity."
The stand-off comes as the Philippines prepares for joint naval exercises with the United States from the 16 to 27 April near the disputed area.
Six countries claim competing sovereignty over areas in the South China Sea, which is believed to contain huge deposits of oil and gas.
Along with China and the Philippines, they are Brunei, Malaysia, Vietnam and Taiwan.
China's claim includes almost the entire South China Sea, well into what the UN Convention on the Law of the Sea recognises as the 200-mile-from-shore Exclusive Economic Zones of other claimants.
That has led to occasional flare-ups and to competition to occupy islands, reefs and sandbars.
