A Philippine soldier stands guard next to a pier in Masinloc, Zambales, 230 kilometers away from the South China Sea island of Huangyan on Friday. Protesters planned to leave from Masinlic for a trip to the island. Photo: AFP

China said Friday that it would remain on "high alert" around Huangyan Island in the South China Sea to prevent provocations after Philippine President Benigno Aquino III stopped a group of about 20 Philippine protesters from landing on the shoal.

"Huangyan Island is part of China's territory, China will remain on high alert over the island to prevent any provocative behavior," China's foreign ministry spokesman Hong Lei told a regular news briefing.

"We also hope that the Philippine side will stop making irresponsible remarks and inciting radical behavior, come back to the right diplomatic track, and send clear and consistent messages," Hong said.

A group of about 20 people, led by outspoken former Philippine Marine officer Nicanor Faeldon and including television crews, was set to depart to Huangyan Island from the northern Philippine coastal town of Masinloc before receiving a last-minute call from the president to postpone their voyage.

Faeldon has served time in prison and was discharged from the Philippine Marines for a 2003 coup attempt. The protesters were planning to stay at Huangyan Island for at least three days and fish there.

The Philippine foreign ministry said on Thursday it did not want the trip to go ahead but Faeldon initially ignored the call.

"Given that both China and the Philippines have so far failed to make any substantial concessions over the dispute, if the retired Philippine officer had landed on Huangyan Island, it would have been seen by the Chinese side as an open provocation, and all the previous diplomatic efforts would have been in vain," said Li Guoqiang, deputy director of the Chinese Borderland History and Geography Research Center at the Chinese Academy of Social Sciences.

"Aquino does not basically oppose Faeldon's behavior," Li told the Global Times. "The Philippines has been acting as if it was being bullied by China in this dispute. But if Faeldon made his trip, it would be regarded by the international community as an obvious defiant step, which is not on Aquino's agenda."

Faeldon said the president told him that Philippine government representatives were currently in China to negotiate the maritime dispute.

"He said that he believed the postponement of this activity might be better for the resolution of this dispute," Faeldon told AFP.

Separately, Aquino on Wednesday appointed two special envoys to China to help arrange Philippine senior officials visiting China and to seek more investment and tourists.

On Friday morning, China's Yuzheng 310 fishing patrol vessel reportedly successfully prevented three unspecified foreign gunboats from attacking five Chinese fishing boats in the South China Sea.

Many observers regard the recent Philippine moves as a compromise to economic pressures from China, which has tightened quality controls on Philippine fruit and cut the number of tourist visits to the Philippines.

But Philippine Economic Planning Secretary Arsenio Balisacan said Thursday that the dispute is "likely to have a modest impact (on the economy) as of now," according to Reuters.

"We need to intensify our efforts to diversify our trade with other countries, whether or not this event with China occurred," Balisacan said.

"The move is not because of China's economic pressures. The fundamental reason is that Philippine people do not stand together with the Aquino administration," said Sun Xiaoying, a researcher on Southeast Asian nations at the Guangxi Academy of Social Sciences.

"Just look at the number of people who protested the US submarine docking at the Philippine port. It was far more than the number of protesters in front of China's embassy in Manila days ago," Sun added.

"It looks like Aquino's administration is bowing to economic pressure. But the truth is that Aquino is looking for an excuse to step backward."

Philippine official data shows China is the Philippines' third-biggest export market after Japan and the US, accounting for around 14 percent of total shipments in the first quarter of this year.

Agencies contributed to this story