A painting of political cartoonist Zunar in George Town, depicting him as being silenced by Umno following the cancellation of his shows in Penang, has been vandalised by an unknown individual.

The artist who posted the piece on a side alley next to Hin Bus Art Depot on Lebuh Gurdwara in George Town, who only wished to be known as Bibicun, said: "I don't see it as ruined, but as a reaction. It does not matter who is reacting to it.

"The initial piece was a response to the suppression of Zunar's exhibition at Penang Literary Festival last year. I'm surprised it took them (Umno supporters) such long time to respond.

"I'm still figuring out the idea of self-censorship, as partly, I was celebrating Umno's power of authority, rather than siding with Zunar."

A man was seen defiling the caricature that looks like an armless Zunar, whose lips are covered with an Umno flag.

In an artistic response to the damaged artwork, Bibicun replaced it with a modified painting, of a black figure wearing a helmet with Umno's symbol on it hugging Zunar from the back.

Zunar said there is phobia about cartoonists like him in Penang now.

"I am now the target, but it won't stop me from doing my job," the award-winning cartoonist said.

He was forced to abort his exhibition, featuring 50 pieces of his artworks, when receiving threats from his opponents after a digital poster urging Umno supporters to visit him on Beach Street went viral.

Zunar, whose real name is Zulkiflee Anwar Ulhaque, was supposed to hold the event, dubbed "Ketawa Pink Pink", on Beach Street on July 30.

He was also forced to cancel his exhibition in Komtar in October last year, after he was attacked by a group of Umno supporters who said his cartoons lampooning Prime Minister Najib Abdul Razak and his wife Rosmah Mansor were insulting.

He was arrested under the Sedition Act the next day, and is currently banned from travelling overseas. He is challenging the government's decision in court.

In April 2015, Zunar was slapped with nine charges under the archaic Sedition Act and faces a possible 43 years of imprisonment if convicted simultaneously on all the charges.