Citing aerial monitoring, the National Task Force for the West Philippine Sea, an inter-agency body overseeing Manila’s maritime strategy in the South China Sea, said on Tuesday that a floating platform six metres (19.7 feet) wide and six metres long was located within the shoal.
The structure appeared to be an antenna and individuals were seen on board, the task force said.
It said government agencies would continue to monitor developments and assess the nature, purpose and implications of the installation and related activities within the shoal, which is known as Huangyan Island in China and Panatag Shoal in the Philippines.
The task force also said that the foreign ministry in Manila had undertaken “appropriate diplomatic action” against their counterpart in Beijing.
The Chinese foreign ministry said China had a legitimate right to carry out activities, “including scientific research”, at Scarborough Shoal.