Beijing said on Monday it was "startled" by Manila's recent statement that it would use a warship grounded in Chinese territory as "a permanent Philippine government installation".

"The Chinese government's attitude on maintaining the country's sovereignty and territorial integrity is unwavering. We will never tolerate the Philippines' illegal occupation of the Ren'ai Reef in any form," said Foreign Ministry spokesman Hong Lei said.

"China is on high alert for the Philippines' possibly taking more provocative moves in the South China Sea. The Philippines must accept responsibility for the consequences of what will happen," he said.

Hong was responding to a statement by the Philippine Department of Foreign Affairs last week in which Manila said the country had grounded a warship on the beach of the Ren'ai Reef in 1999 "in response to China's illegal occupation" of Meiji Reef in 1995.

Since 1999, China has repeatedly demanded the Philippines retrieve the warship, but Manila has cited technical reasons for its inability to do so.

The Philippine statement said the grounding happened before the signing of the Declaration of Conduct of Parties in the South China Sea in 2002, and Manila will not move the ship.

Hong said that Manila promised several times in 1999 that it would move the ship. It also promised in 2003 not to become the first country to breach the DOC over the Ren'ai Reef issue.

The Philippines has not only failed to remove the ship but has attempted to bring in construction materials and build permanent structures on the reef, violating its promises and the DOC, Hong said.

"Today's Philippine government is different from that of 15 years ago, but as a country, the Philippines must be responsible for its promises. The country would discredit itself before the international community by publicly violating its own promises," he said.

Earlier this month, Chinese coast guard vessels chased away from Ren'ai Reef two Philippine ships loaded with construction materials.

Chen Qinghong, a Southeast Asian studies researcher at the China Institutes of Contemporary International Relations, said Manila has beefed up its attempt to occupy the reef as neighboring countries have focused on searching for the missing Malaysia Airlines jetliner that disappeared on March 8.

"The Philippines aimed to repair the small and old warship to maintain its presence on the reef, but it can hardly reach the reef. Its moves will only increase the risks of conflict," Chen said.

Chinese vessels that have been efficiently patrolling the reef did not take further moves for the sake of maintaining regional stability, he added.

zhaoshengnan@chinadaily.com.cn