China has launched a vituperative attack on Taiwan’s foreign minister, evoking the words of revolutionary leader Mao Zedong to denounce him as a “shrilling” fly for his efforts to promote Taiwan internationally.

Taiwan Foreign Minister Joseph Wu, a fluent English speaker, is an outspoken supporter of the island’s efforts to push back against pressure from China, which claims Taiwan as its own, and regularly appears on think-tank and other panels.

In a lengthy denouncement of Wu late on Thursday, China’s Taiwan Affairs Office said he was a “diehard” supporter of Taiwan independence who peddled lies that Taiwan is a sovereign country.

It quoted a poem written by Mao in 1963, The River All Red, which was a denunciation of the Soviet Union and the United States.

“All forms of comments on Taiwan independence are but flies ‘humming, with a burst of shrilling and a fit of sobbing,’” the Beijing’s Taiwan Affairs Office said.

Taiwan’s foreign ministry said the attack was “not worthy” of commenting on.

However, Taiwan’s China-policy making Mainland Affairs Council denounced it as “slander and abuse”.

“This kind of verbal violence, unprecedented in the international community, only highlights the overstepping of the rules of the Taiwan-related body on the other side of the Taiwan Strait and how far away it is from civilized society.”

China has stepped up military and political pressure to try and force the democratically ruled island to accept Chinese sovereignty.

Taiwan says it is an independent country and will defend its freedom and democracy.