But while the added figures were approved by a newspaper, Wong said some were fearful of even appearing in the same poster with the duo, particularly since Wong was a strident supporter of the pro-democracy Occupy Central demonstrations in late 2014.

He said the ads were pulled because someone in the poster with business links to mainland China was afraid of appearing with him.

“I do not wish to name the person, as the individual was very scared. So the record label … [concert] organiser decided to [pull the ad],” Wong said on a radio show on Monday.

“My label’s boss said if the individual was so scared, then we should not get in the way of making money [on the mainland].

“The fear is very worrying … I feel it is not right not to speak out [on the issue], otherwise more and more people and incidents will be silenced.”

He described the situation as “ridiculous” and said more “prominent” people had not complained.

“It’s just one photo, one poster, but it reflects the current times we are in,” Wong said in a Facebook post. “This society really has people who fear everything, and their fear has led them to this point, where they are scared to death to even be in the same poster as us.”

He blamed “the invisible hand” of censorship and interference in the industry and said the MTR Corp was not involved in the decision.

The movement for democracy in Hong Kong is being watched warily by the Beijing government, which is openly critical of greater independence for the former British colony as it operates semi-autonomously under the “one country, two systems” framework.

But businesses worried about political reprisals on mainland China have moved to distance themselves from controversial figures endorsing democracy in the city.

During Occupy Central, two of Wong’s November concerts on the mainland were “indefinitely postponed” by organisers.

He told the Post in May 2015 that for six months after Occupy he did not have a single job offer from either the mainland or Hong Kong.

“It was a weird and worrying situation,” he said. “What worries me is that it even happened in Hong Kong because Hong Kong is supposed to be a free city.”

The MTR Corp said adverts were commissioned by third-party agencies and ads are subject to guidelines issued by the industry and needed to comply with the law.

Now, the disappearance of Wong’s concert poster shows the “invisible hand” at work, he said, after experiencing difficulties during the entire process of creating and producing the poster.

He likened its removal to something out of George Orwell’s classic dystopian novel Nineteen Eighty-Four , depicting an authoritarian society whose citizens have little to no agency.

“Just like this poster, there are many people and things in this city that quickly disappear,” he wrote.

Fans took up the Orwell comparison on Facebook. “He continuously wrote: Down with Big Brother! Down with Big Brother!” one user commented.

“Many people support you ... See you at the end of March,” another wrote.

Ho also posted messages on her Facebook page, saying the incident showed “the self-censorship of the entertainment industry has reached a level beyond that described in 1984”.

Wong called on his fans to help fill every seat for his concert.

“Let us continue to dance and make music, challenging these most evil of times,” he said