BEIJING -- China firmly opposes any construction activities by the Philippines on Chinese islands and reefs in the South China Sea illegally occupied by the Philippines, a Chinese defense spokesman said on Monday.

Jiang Bin, a spokesman for China's Ministry of National Defense, made the remarks in response to reports that satellite imagery showed the Philippines accelerating infrastructure construction on occupied islands and reefs in the Nansha Islands.

"China has indisputable sovereignty over the Nansha Islands and their adjacent waters," Jiang said at a press briefing.

"We firmly oppose the Philippine side carrying out construction activities on all illegally occupied Chinese islands and reefs, including Zhongye Island and Mahuan Island," he said.

Jiang added that China will take necessary measures to safeguard its territorial sovereignty and maritime rights and interests.