The Chinese military strongly protests a high-altitude US spy plane trespassing into the no-fly zone that is currently hosting a live ammunition drill by the People's Liberation Army Northern Theater Command, Senior Colonel Wu Qian, spokesman of the Ministry of National Defense, said in a statement on Tuesday.

PLA Air Force flies a bomber to conduct island patrols over the South China Sea in this file photo taken on Nov 23, 2017. (Photo: Xinhua)

On Tuesday, a Lockheed U-2 high altitude reconnaissance aircraft trespassed into the no-fly zone, and "seriously disrupted China's routine training activities," Wu said, adding the maneuver also seriously violated China-US maritime and flight safety codes and international norms.

"The incident can very easily lead to misunderstanding and misjudgment, and may even lead to an accident," he said. "It is also a blatant act of provocation that China resolutely opposes."

Wu said China has urged the US to stop similar provocations, and take concrete actions to maintain regional peace and stability.

According to local maritime safety administrations, China is currently hosting military drills in three of its adjacent waters, including the Bohai Sea, the Yellow Sea and the South China Sea.

The exercise in the Bohai Sea, which is the northwestern and innermost gulf of the Yellow Sea bounded by the coastlines of Hebei, Shandong and Liaoning provinces, began Friday and ends Friday. The drill in the South China Sea began Monday and ends Saturday.

The PLA Eastern Theater Command said on Monday that its naval aviation units recently conducted full-day exercises in the East China Sea.