The Philippine warship then left and the Chinese fishermen returned home on Friday.

But it is reported that Manila has sent patrol ships to waters near the island following the departure of the warship. A Philippine archaeological research ship was also in waters near the island and Beijing on Monday requested the ship to leave.

On Wednesday morning, China's fastest fishery administration vessel Yuzheng 310 left Guangzhou to cruise on the South China Sea.

"This is aimed to better protect Chinese fishermen's rights and marine resources," said an anonymous official from the South China Sea Fishery Bureau.

The ship's destination has not been revealed.

China recently stepped up its patrols in the South China Sea. The Yuzheng 44061, left Zhanjiang port in Guangdong province on Sunday to waters around the Nansha Islands.

Yang Baoyun, a professor of Southeast Asian studies at Peking University, said that Manila is playing tricks to make the dispute an international issue.

"Manila said it wanted a peaceful resolution while it continues to keep vessels in China's territorial waters," Yang said.

Beijing's decision to send more patrol ships is a necessary and justified step to show strength, analysts said. "The move also sends the message to Manila that Beijing does not make concessions after China has shown patience and sincerity to avert the situation from deteriorating," Zhang Tuosheng, an expert on international relations at the China Foundation for International and Strategic Studies, said.