A convoy of boats carrying Philippine civilians bearing supplies for Filipino fishers has abandoned plans to sail closer to a China-held reef off the Southeast Asian country, organizers said Thursday.

The convoy set sail Wednesday to distribute fuel and food to fishers and assert Philippine rights in the disputed South China Sea. The trip comes two weeks after China Coast Guard vessels used water cannon against two Philippine government boats near Scarborough Shoal.

Atin Ito ("This Is Ours") coalition spokesman Emman Hizon declared "Mission accomplished", telling reporters Thursday that an "advance team" had already distributed fuel and other assistance to Filipino fishermen a day earlier about 46-56 kilometers (29-35 miles) from the disputed shoal.

"Atin Ito will now proceed to conduct the final leg of supply distribution in the current area, as there are no more Filipino fishers in BdM," he said, using the acronym for the shoal also known to Filipinos as Bajo de Masinloc.

Hizon said in a message to reporters that the group had received reports that fishing boats in the area were "sent away by various Chinese vessels".

The Chinese foreign ministry had warned the convoy on Wednesday against any attempt to infringe on Beijing's "indisputable sovereignty" over Scarborough Shoal.

An aerial reconnaissance flight saw 19 Chinese vessels including a warship and eight coast guard vessels patrolling around the shoal on Wednesday, the Philippine Coast Guard said.

The Filipino aid convoy, comprising four wooden-hulled fishing boats and a coast guard escort, was about 108 kilometers southeast of Scarborough Shoal at 6:00 a.m. (2200 GMT Wednesday).

It was being tracked by a nearby China Coast Guard vessel, the Philippine Coast Guard said.

"Despite China's massive blockade, we managed to breach their illegal blockade, reaching Bajo de Masinloc to support our fishers with essential supplies," the head of the coalition, Rafaela David, said in a statement.

The Scarborough Shoal has been a potential flashpoint since Beijing seized it from Manila in 2012.

The fish-rich reef is about 240 kilometers west of the Philippines' main island of Luzon and nearly 900 kilometers from Hainan, the nearest major Chinese land mass.

China claims almost the entire South China Sea, brushing off rival claims by the Philippines and other countries, and ignoring an international ruling that its assertion has no legal basis.

To press its claims, Beijing deploys coast guard and other boats to patrol the waterway and has turned several reefs into artificial islands that it has militarized.