The Filipino aid convoy, comprising four wooden-hulled fishing boats and a coast guard escort, was about 108km southeast of Scarborough Shoal at 6am.
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 240km west of the Philippines’ main island of Luzon and nearly 900km 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 militarised.
