China expressed anger on Monday after about 50 Filipino protesters reached the disputed Pagasa island in the South China Sea and said that they would stay there for three days as an act of defiance.
South China Sea, which is believed to contain huge deposits of oil and gas, is claimed by China, Brunei, Malaysia, the Philippines, Taiwan and Vietnam.
Chinese Foreign Ministry spokesman Lu Kang said China was “strongly dissatisfied” with what the Filipino protesters, which include many students, have done.
"We once again urge the Philippines to withdraw all its personnel and facilities from the islands that it is illegally occupying, refrain from actions that are detrimental to regional peace and stability and not conducive to Sino-Philippines relations," Lu added.
The group, led by an ex-marine captain tried to sail to the disputed Pagasa island in early December, but was stopped by officials for security and safety reasons after a storm in the South China Sea.
However, the group sailed 500 km (310 miles) and reached the Pagasa island in the Spratly archipelago on Saturday after they released a statement on Facebook.
"We encourage the highest leadership of the country to inform the people correctly without sugar-coating the truth about Chinese invasion of our Exclusive Economic Zone," the protesters wrote.
The government officials of Philippines are concerned about relations with China after the latest protest.
The Philippines has filed territorial claims against China in 2013 at an arbitration court in the Netherlands. Beijing has not recognized the case.