BEIJING (Reuters) - China said on Monday that coast guard ships had driven away two Philippine vessels which had tried to approach a shoal in the South China Sea in the latest flare-up of a long-running territorial dispute.
The Chinese ships were patrolling waters around Second Thomas Shoal, known in China as the Ren'ai reef, when they spotted the Philippine boats, carrying construction materials and Philippine flags, which left the area after being warned off, Chinese Foreign Ministry spokesman Qin Gang said.
The incident happened on Sunday, he added.
Qin said that China had repeatedly demanded the Philippines remove a ship which had been grounded on the shoal in 1999, but that Manila had cited technical reasons for being unable to do so.
"This time, the Philippine side has again attempted to start construction on the reef," he told a daily news briefing. "The moves infringed China's sovereignty."
China had no choice but to respond to the Philippines' moves, Qin added.
Manila ran aground an old transport ship on the reef in 1999 to mark its territory, and has stationed marines in abject conditions on the rusting ship.
China's claims over islands, reefs and atolls in resource-rich waters off its south coast and to the east of mainland Southeast Asia have set it directly against Vietnam and the Philippines, while Brunei, Taiwan and Malaysia also lay claim to parts.
The Second Thomas Shoal, a strategic gateway to Reed Bank, believed to be rich in oil and natural gas, is one of several possible flashpoints in the South China Sea that could force the United States to intervene in defense of its Southeast Asian allies.
In 2010, Manila awarded an Anglo-Filipino consortium a license to explore for gas on Reed Bank, but drilling stalled in 2012, because of the presence of Chinese ships.
Manila says Reed Bank, about 80 nautical miles west of Palawan island at the southwestern end of the Philippine archipelago, is within the country's 200-nautical mile exclusive economic zone.
Beijing says it is part of the Spratlys, a group of 250 uninhabitable islets spread over 165,000 square miles, claimed entirely by China, Taiwan and Vietnam and in part by Malaysia, Brunei and the Philippines.
(This version of the story adds "again" to quote in the fifth paragraph)
(Reporting by Ben Blanchard)