A Chinese coast guard vessel Sunday drove away two Philippine ships carrying construction materials from the Ren'ai Reef of China's Nansha Islands, China's state-run Xinhua News Agency reported.
The Philippines Tuesday launched a protest against the incident.
"The Foreign Ministry has summoned the head of the Philippines embassy in China to lodge solemn representation on this event," Foreign Ministry spokesman Qin Gang said.
In 1999, a Philippines warship grounded on the beach of the Ren'ai Reef. China has repeatedly asked the Philippines to remove the ship, but the Philippines have said it is immovable due to technical reasons.
China accused the Philippines in February of trying to make a move on the Huangyan Islands, Xinhua said.
"Our will and resolve in safeguarding territorial sovereignty is unswerving, and China resolutely opposes any move that will complicate and expand the situation," Defense Ministry spokesman Yang Yujun told a press conference at that time.