The Philippine Coast Guard on Sunday accused Chinese vessels of "dangerous" manoeuvres during a nine-day patrol near a reef off the coast of the Southeast Asian country.

The Philippine vessel BRP Teresa Magbanua was sent in early February to patrol the waters around Scarborough Shoal, a rich fishing ground in the South China Sea, and deliver provisions to Filipino fishermen and ensure their safety.

The reef has been a flashpoint between the countries since China seized it from the Philippines in 2012.

Since then, Beijing has deployed patrol boats that Manila says harass Philippine vessels and prevent Filipino fishermen from reaching the lagoon where fish are more plentiful.

During the patrol, Chinese Coast Guard (CCG) vessels "performed dangerous and blocking manoeuvres at sea against BRP Teresa Magbanua four times, with the CCG vessels crossing the bow of the PCG vessel twice", the Philippine Coast Guard said in a statement.

The Philippine Coast Guard said its ship was also "shadowed" by four Chinese Coast Guard vessels "on more than 40 occasions".

The coast guard also observed what it described as "four Chinese Maritime Militia vessels".

China Coast Guard spokesman Gan Yu hit back, saying the Philippine vessel had "illegally intruded" into the waters several times.

"The China Coast Guard, noting that the warnings it had issued had proved ineffective, took action in accordance with the law to control the progression of the Philippine vessel and force it to leave," Gan said.

"The China Coast Guard dealt with the incident professionally and to standard," he added.

Videos released by the Philippine Coast Guard show a Chinese Coast Guard vessel metres from the port beam of the BRP Teresa Magbanua, before it crosses the path of the Philippine boat.

Scarborough Shoal is 240 kilometres (150 miles) west of the Philippines' main island of Luzon and nearly 900 kilometres from the nearest major Chinese land mass of Hainan.

The incidents came two months after tense standoffs between China and the Philippines around disputed reefs in the South China Sea that saw a collision between vessels from the two countries and Chinese ships blasting water cannon at Philippine boats.

China claims almost the entire sea and has ignored an international tribunal ruling that its assertions have no legal basis.

It deploys boats to patrol the busy waterway and has built artificial islands that it has militarised to reinforce its claims.

Chinese and Philippine officials last month agreed on the need for closer dialogue to deal with "maritime emergencies" in the waterway as tensions escalated.