One of two Lindauer paintings stolen in a brazen heist earlier this year has appeared for sale for $1 million on the dark web.

Photo: RNZ / Laura Tupou

The Gottfried Lindauer paintings Chief Ngatai-Raure and Chieftainess Ngatai-Raure were taken from a Parnell art gallery in a ram-raid in April.

Dr Ngarino Ellis, who is a lecturer in Art Crimes at Auckland University, said she was contacted by a UK journalist who had discovered the Chief Ngatai-Raure painting on the 'White Shadow' market, a dark web auction site.

She said the screen shots of the auction were very concerning.

The paintings had been taken out of their frame and had a post-it-note with the date stuck to the front.

Photo: Supplied

Dr Ellis said that could be an indication the paintings were genuine, as most true art pieces were sold without a frame, so buyers can see the edges of the canvas.

She was stunned at the audacity of the seller, who clearly states the paintings were stolen, and she said that means whoever buys it cannot claim to have been unaware of its origins.

As far as Dr Ellis was aware, this was the first time a New Zealand painting has been auctioned off on the dark web, but she said this was proof that there was a black market for art antiquities from New Zealand and the Pacific.

She said the painting had a $1 million buy-now price tag and so far had two bids, with the leading bid for $400,000. She said the way the artwork was taken meant there were shards of glass in the work, which could affect the value - unless there was a good conservator involved.

Dr Ellis said police were aware of the auction and she was hopeful they would be able to track the thieves down through this latest lead.

The auction was due to run until 28 December.