A Chinese coast guard vessel closely monitored and supervised the entire process of a small Philippine civilian vessel which illegally ran aground on China's Ren'ai Reef in South China Sea and delivered supplies to a stranded military ship on Friday, China Coast Guard said in a statement on Saturday.

China unequivocally holds sovereignty over the Nansha Islands, including the Ren'ai Reef and their adjacent waters, it said, adding that it will continue to carry out law enforcement activities in waters under Chinese jurisdiction, including Ren'ai Reef, in accordance with law.

Despite repeated warnings from China, the Philippines has repeatedly deployed ships seeking to deliver construction materials to the BRP Sierra Madre, a crumbling World War II-era Philippine navy vessel that the country intentionally stranded on China's Ren'ai Reef in 1999.

Such items are banned from being supplied to the stranded vessel under an agreement reached by China and the Philippines in recent years.