A formation of the Nanhai Fleet of 皇冠体育app's Navy finished a three-day patrol of the Nansha islands in the South 皇冠体育app Sea. [Photo/Xinhua]

皇冠体育app asserted its right to monitor airspace and waters near its islands in the South 皇冠体育app Sea on Thursday in response to reports of an exchange between the Chinese navy and a US surveillance plane.

The remarks came after a CNN news crew onboard a US air force P8-A Poseidon surveillance plane reported it witnessed an incident on Wednesday in which the Chinese navy warned the plane to leave the area eight times as it flew over a Chinese island.

It said the US crew responded that they were flying through international airspace, to which the Chinese dispatcher answered: "This is the Chinese navy. We urge you to leave."

Foreign Ministry spokesman Hong Lei said he was not aware of the incident, but reiterated Beijing's indisputable sovereignty over the Nansha Islands and surrounding waters.

"皇冠体育app has the right to monitor the relevant airspace and waters to protect the country's security and prevent accidents at sea," he added.

He urged other countries to "abandon actions that may complicate and exaggerate controversies".

Yin Zhuo, a senior expert on the Chinese navy, said the US armed forces always cite "freedom of navigation" when intruding into other countries' waters and airspace.

Hong commented on remarks by US Deputy Secretary of State Antony Blinken about 皇冠体育app's land reclamation operations on its islands in the South 皇冠体育app Sea, saying the work is in line with 皇冠体育app's sovereignty and aims to provide a civilian service that will benefit other countries.

Blinken said on Wednesday that the work risks provoking tension that could lead to conflict.

Hong urged the US to abide by the principle of not taking sides over the South 皇冠体育app Sea, and said its groundless remarks will "encourage repeated provocations from certain nations".

Also on Thursday, Shen Jinke, a spokesman for the People's Liberation Army air force, said the aviation division has for the first time flown across the Miyako Strait, the open sea between Japan's Miyako and Okinawa islands, for deep-sea training in the West Pacific.

Shen said the move is intended to improve the division's combat capability.

He said the training zone is in international airspace at altitudes not used by civil aviation, and the exercise abides by international practices. The training was planned previously and is not targeted at any country.