A controversial work of art featuring an archetypal gang patch is expected to sell for more than $200,000 at auction in Auckland next week.

Blackout Movement, by leading contemporary and Maori artist Shane Cotton, is a 4.8m by 1.6m painting which has been part of a private collection since being exhibited as a new work in 2001.

But Auckland auction house Webb's - which hopes to sell the painting for between $200,000 and $300,000 - says two institutions are considering buying it and expects the auction to attract international interest.

"It is a very strong contemporary painting - it really deals with key themes around affiliation, belonging, exclusion and indoctrination," Webb's managing director Neil Campbell said yesterday.

Those themes centred on the gang patch, which he described as a strong cultural "identifier".

"There's a real fascination in terms of what the patch is, and there's a real fetish I think which goes along with people's interest in the gangs."

As well as the patch, the painting contains finely detailed calligraphy or "tagging" pointing to a range of tribes and gangs, along with religious scripture.

Its auction follows the sale of another Cotton painting last year, Wake, for $205,000 before GST.

But although it can safely be assumed that Wanganui's Sarjeant Art Gallery is not among prospective purchasers of Blackout, given its tight financial position if not the city's ban on wearing gang patches, Mayor Michael Laws said he saw no problems with the painting.

"Modern art is the dissection of horses, it is in many cases the pursuit of ugliness - this seems to be just par for the course and if he can parlay that into some money, good luck to him," he told the Herald, while questioning the newspaper's interest in his opinion on art. "I'm not going to get upset about a painting of a gang patch - that would be ridiculous."

Just as Mr Laws refused to let his council shut down a controversial exhibition at its gallery in 2005 featuring stylised swastikas, he said it would not concern him if the Cotton painting was shown in his city.

"It doesn't worry me, he's not a member of a criminal gang," he said of the artist.

Mr Campbell said the recession had not dampened his firm's business, which included an 8 per cent increase in revenue from sales of fine art over the past 12 months.