BEIJING (UPDATE 1) - A third Chinese patrol ship arrived Friday in disputed waters off the Philippine coast, China's state media said, drawing protests from Manila which accuses Beijing of escalating a 10-day stand-off.
The Philippines and China have both dispatched vessels as they lay claim to a group of islands in the South China Sea that is about 120 nautical miles west of the main Philippine island of Luzon.
It is one of the most high-profile flare-ups in recent years between the two countries over their competing territorial claims to parts of the South China Sea, which is believed to sit atop vast oil and gas deposits.
The row erupted last week when Chinese vessels blocked a Philippine warship from arresting crews of Chinese fishing boats in the area and spiked this week when Chinese boats were accused of harassing a research ship.
Beijing, however, claims the warship hassled the fishing boats, which it says were taking refuge from harsh weather in a lagoon. China has also urged the archaeological research vessel to "leave the area immediately".
China has already sent several civilian patrol boats to the disputed group of islands known in the Philippines as Scarborough Shoal and called Huangyan Island in Chinese.
On Friday, a 108-metre (350 feet) high-tech patrol ship also arrived to "protect the country's interests in territorial waters", the state Xinhua news agency said, bringing to three the number of Chinese boats in the area.
"The Yuzheng-310 will conduct routine patrols in waters off the coast of Huangyan Island, so as to protect China's sea rights and ensure the safety of Chinese fishermen," it quoted the South China Sea Fishery Bureau as saying.
The bureau was unavailable for comment on Friday.
Philippine foreign department spokesman Raul Hernandez said the arrival of a third Chinese vessel ran contrary to efforts by the two rival claimants to seek a diplomatic solution to the dispute.
"Let us not aggravate this by any action that would escalate the situation. And we think this is an action that aggravates and escalates the situation," he told reporters.
"So in our next talk, we will ask China why they are trying to do this, and ask why they have violated our agreement not to aggravate, not to escalate, the situation in the Scarborough Shoal."
China says that it has sovereign rights to all of the South China Sea, even waters close to the coast of other countries and hundreds of kilometres from its own landmass.
The Philippines says it has sovereign rights over areas of the sea within its 200-nautical-mile exclusive economic zone, and that its position is supported by international law.