A fish farm is seen in the waters at Meiji Reef of the South China Sea. /Xinhua Photo

China's Ministry of National Defense spokesman Ren Guoqiang said on Thursday that two Chinese warships warned a US Navy warship to leave after it sailed within 12 nautical miles of Meiji Reef of China's Nansha Islands in the South China Sea.

Speaking at a monthly news briefing in Beijing, Ren Guoqiang said that China had lodged stern representations to the US over the patrol and that such moves were not conducive to peace and stability in the South China Sea.

Reuters reported earlier, quoting unnamed US officials, that the operation was led by the USS Dewey under the “Freedom of Navigation” principle and is the first of its kind since US President Donald Trump took office.

China’s Foreign Ministry spokesman Lu Kang said on Thursday that China urged the US to correct its mistake and refrain from further patrols. He added that China and ASEAN countries have recently cooperated to ease tensions over the South China Sea, but such actions by the US were very likely to cause unexpected air and sea accidents.

Beijing has condemned similar moves by the US in the past, as they encroach on China's sovereignty and could risk flaring up tensions in the maritime body.

According to the UN Convention on the Law of the Sea, territorial waters are defined as extending at most 12 nautical miles from a state’s coastline.

The last similar US patrol was in October 2016, when a US guided-missile destroyer USS Decatur traveled near Xisha Islands in the South China Sea, a move described by the Chinese Defense Ministry as "illegal" and "provocative." At the time, two Chinese warships warned the US navy to leave.

The US began to conduct what it calls “Freedom of Navigation” operations in the South China Sea in October 2015, with US navy ships sailing within 12 nautical miles of China's Nansha Islands.

China's Ministry of National Defense spokesman Wu Qian said in April of last year that the operations were “very dangerous,” noting that they were “political and military provocations against China and would easily lead to unexpected incidents.”

Last month, top US commander in the Asia-Pacific region, Admiral Harry Harris, said the United States would likely carry out "Freedom of Navigation" operations in the South China Sea soon, without offering any details.