A NEVER-BEFORE-SEEN sculpture by mysterious graffiti artist Banksy has been unveiled at the Walker Art Gallery.

The work, a defaced 18th-century replica stone bust, had previously been kept a closely guarded secret from all but a select group of gallery staff.

Believed to be a comment on the Church’s abuse cover-up, it is controversially placed among 17th- century altar pieces and religious paintings.

Banksy, whose true identity is unknown, said: “I guess you could call it a Christmas present.

“At this time of the year, it’s easy to forget the true meaning of Christianity – the lies, the corruption, the abuse.”

He praised the Walker, to which he has donated the art work on an indefinite basis.

He said: “I love everything about the Walker Gallery – the Old Masters, the contemporary art, the rude girl in the cafe.

“And when I found out Mr Walker built it with beer money, it became my favourite gallery.”

The defaced sculpture is only the second of Banksy’s works to be in a gallery, after a 2009 showing of his work in the Bristol Museum and Art Gallery, which attracted nearly 4,000 people per day.

The 18th-century replica stone bust, entitled Cardinal Sin, has had its face sawn off and replaced with bathroom tiles.

They create a pixelated effect, giving the impression of media images of suspected criminals.

Reyahn King, director of Art Galleries, said Banksy had asked that his sculpture was placed within the gallery’s period collection.

She said: “We were very happy to oblige.

“We are thrilled to display the work of this major contemporary artist.

“It is a huge coup and we’re sure his work will spark a reaction with visitors.”

The unveiling comes just days after another apparent Banksy piece was discovered in Liverpool.

A bi-plane trailed by a chain of smoke was found earlier this week on a wall in a car park on Rumford Street.

Photographs of the graffiti have appeared on the artist’s own website, suggesting they are authentic, and it is almost identical to one that was spotted in Tower Hamlets in London last week.

A day later, the piece was vandalised, with the words “BANKSY 4 ROBBO” spray-painted over it.

Banksy also has another piece on display in Liverpool – a giant rat painted on the outside of the Whitehouse Pub, on Berry Street, painted to coincide with the 2004 Liverpool Biennial festival of contemporary art.