BEIJING, July 15 -- China on Wednesday protested against the Philippines' consolidation of its illegally "stranded" warship on a Chinese reef in the South China Sea.

The Philippine navy is "quietly reinforcing the hull and deck of a rusting ship" it ran aground on Ren'ai Reef, which the Philippine Foreign Ministry spokesman Charles Jose said is "for the safety of its personnel and safety of navigation," according to media reports.

"China expresses strong protest and firm opposition to the reinforcement of the warship," Foreign Ministry spokeswoman Hua Chunying said, reiterating China's sovereignty over the Nansha Islands and surrounding waters.

Hua recalled how the Philippine warship illegally landed on the beach of the Ren'ai Reef of China's Nansha Islands in 1999 under the excuse that it had been stranded.

Since then, China has repeatedly lodged protests and representations to the Philippines, demanding that the country tow the warship away, Hua said.

The Philippine side has said that it will not be the first country to violate the Declaration on the Conduct of Parties in the South China Sea (DOC), and has not dragged the warship away because of a "lack of parts," stressing that the country does not have any intention of building any facilities on the reef, Hua said.

"But the Philippines have not only failed to deliver on its promise to tow away the ship but is increasing illegal activities on the reef in an attempt to occupy it forever," she said.

"The Philippine side has broken its own promise and lost the trust of the international community," said the spokesperson.

"Its behavior fully reveals its hypocrisy and dualistic character, and proves that the Philippines is the real trouble maker and rule breaker in the region," Hua said.

China is determined to safeguard its national territorial sovereignty and maritime rights and interests, she said.

"We urge the Philippine side to immediately stop these violations and fulfill its promise," said the spokesperson.

China maintains the right to take further measures, she added.