China's foreign ministry expressed anger on Monday over two U.S. warships entering the South China Sea.

The two warships entered China's territorial seas around the Nansha Islands without permission from the Chinese government, ministry spokeswoman Hua Chunying said at a daily news briefing.

The Chinese side immediately conducted verification and identification on the U.S. ships and warned them to leave, said the spokeswoman.

The relevant action by the U.S. side infringed upon China's sovereignty, and undermined the peace, security, and order of the relevant waters, Hua said, adding that China will continue to take necessary measures to safeguard itself.

China firmly opposed the relevant action and urged the U.S. to immediately stop its provocations, Hua stressed.