The Natural History Museum's wildlife photographer of the year has been stripped of his £10,000 prize, after judges found he was likely to have hired a tame Iberian wolf to stage the image of a species seen rarely in the wild.

The judges of the award, which attracted more than 43,000 entries from 94 countries, said they were convinced José Luis Rodriguez hired the wolf called Ossian from a Madrid wildlife park, contradicting his claim the image was taken in the wild after months of patient tracking of the dwindling species.

Competition rules prohibit the use of animal models and this morning organisers took down Rodriguez's image from the exhibition at the museum in London, banned him from entering the contest again and announced they were "saddened" by the disqualification. Apparently without irony, he had titled his image The Storybook Wolf, but headline writers have since dubbed it the "loan wolf".

Rodriguez could not be contacted, but the competition organisers said he continued to strongly deny the wolf was tame.

"I remember thinking, my God, this really is a wild wolf, what an achievement," said Mark Carwardine, chairman of the judging panel. "I don't understand the mentality at all. People feel very disappointed with the photographer."

The organisers said they were planning to erect a notice at the Natural History Museum explaining to visitors their belief that the photo was staged, although it is too late to remove the image from the thousands of books that have been published by BBC Worldwide.

The controversy is thought to be the first time the competition's expert judging panel have allowed an animal model to win a prize and there was concern the revelation could damage a contest which has a reputation as the most prestigious of its kind in the world.

"The wildlife photographer of the year is the one institution that has pushed us [animal photographers] to be more creative, so it is very sad it has happened to this competition," said Chris Gomersall, a wildlife photographer who was involved in judging.

"In wildlife photography there are ethical guidelines and there has always been an explicit understanding that if you take pictures of a captive subject, you declare it on your caption."

Rodriguez had told the judges he had sketched the shot he wanted to get on paper, but "couldn't quite believe it when he got the shot of his dreams". He said his main fear had been that the wolves "would be too wary".

Jim Brandenburg, a judge and a wildlife photographer with 45 years experience of taking pictures of wolves, marvelled at the image of the animal, captured so clearly and apparently hunting a farmer's livestock. He declared it "a masterfully executed moment", but having studied pictures of Ossian and Rodriguez's image, he is now "99.9%" sure it is a tame wolf, according to Carwardine.

The organisers were alerted to suspicions about the image by Spanish photographers who recognised the wolf and the location as the Cañada Real wildlife park. Wolf experts also questioned why the wolf would jump the gate when a wild animal was more likely to squeeze between the bars.

The judges said they asked Rodriguez for corroboration of his story and if there was anyone who could act as a witness to back him up, but his answers were inadequate.