13 June 2015, 13:07 GMT
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," Xinhua news agency reported on Wednesday.
"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.
The Philippine warship illegally landed on the beach of the Ren'ai Reef on China's Nansha Islands in 1999 with 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 refuses to drag the warship away due a "lack of parts," arguing it has no intention to build any facilities on the reef.
China maintains the right to take further measures, Hua warned.
