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

The Foreign Ministry unveiled further details on Friday and voiced China's "strong dissatisfaction" about a close encounter on Wednesday involving a US spy plane above the South China Sea.

The incident involved a US army P-8A surveillance plane that flew near islands and reefs including the Yongshu Reef of China's Nansha Islands, on a reconnaissance mission, ministry spokesman Hong Lei told a daily news conference in Beijing on Friday.

A CNN news crew onboard the US plane reported that the Chinese navy warned the plane to leave the area eight times as it flew over a Chinese island.

The Chinese forces then "drove them off with warnings through radio transmissions in accordance with regulations", Hong said.

The close-in reconnaissance "poses potential threats to the security of Chinese islands and reefs, and may easily lead to miscalculation and prompt further unexpected incidents in the sea or airspace", he said.

The US actions were "very irresponsible and very dangerous, sabotaging regional peace and stability", he added.

China wants the US to "strictly abide by international law and relevant international rules, and not to take any risky and provocative actions", he said.

China will continue to keep a close watch over the relevant maritime and airspace situation, and "will take appropriate and necessary measures as the situation requires" to prevent cases occuring either on sea or in the air that could endanger the security of China's islands and reefs, Hong said.

Contact the writer at zhangyunbi@chinadaily.com.cn