WILDCATS on display at two of Scotland's best-known zoos are not pure-bred animals but hybrids of little conservational value, according to an expert.

Edinburgh Zoo and Highland Wildlife Park at Kincraig, near Aviemore, both of which are run by the Royal Zoological Society of Scotland, house the species, with its literature stating the animals are "one of Britain's rarest mammals ... in serious danger of extinction" with as few as "400 left".

The website for Edinburgh Zoo says it has four Scottish wildcats while at the Highland Wildlife Park there are said to be six - two males, two females and two unsexed kittens.

But Steve Piper, an independent wildcat expert who was a founder and former chairman of the Scottish Wildcat Association, claims leaked information from the society showed that over a four-year period, 16 kittens were bred by the Zoological Society, 13 were neutered and two died.

He said this shows the society's programme is breeding hybridised cats.

Mr Piper pointed to an entry in 2012 on the society's Highland Tiger website, which carried news about wildcat conservation.

It quotes Douglas Richardson, the organisation's head of living collections at Highland Wildlife Park, as saying: "We have also applied this three-way test to our resident cats at the Highland Wildlife Park, and it came as no surprise that the majority of our 'wildcats' proved to be of hybrid origin to one degree or another; the same is very likely true for the majority of the captive population within the UK."

The latest birth of kittens was announced in August.

Mr Piper, who said there could be as few as 35 pure wildcats left, said: "This appears nothing but commercial exploitation of the wildcat."

He said the Royal Zoological Society of Scotland had generated tens of thousands of pounds of public donations and also grants from Scottish Natural Heritage (SNH) for wildcat conservation in recent years. He said there was no value in conserving hybrids.

But a spokesman for SNH said: "We may find all our wildcats have some degree of shared ancestry with domestic cats. Domestic cats have, after all, been in Great Britain for more than 2,000 years. Nevertheless, the partnership behind the plan agrees these distinct wildcats, even if not genetically 'pure', are worthy of protection."

Liz Tyson, director of the Captive Animals Protection Society, said: "We believe the concerns over the society's breeding of hybridised Scottish wildcats should be investigated as a matter of urgency and the results made public so people can make informed decisions over any future support of the zoos."

Dr Rob Ogden, director of conservation at the Royal Zoological Society of Scotland, said: "The views expressed confuse different aspects of the Scottish wildcat Conservation Action Plan (SWCAP) which is backed by a wide range of partners in government and NGOs, of which RZSS is a key member. RZSS' role in this programme is to lead on genetic management, animal husbandry and to inform and engage the public through the presence of cats at Highland Wildlife Park.

"The cats historically kept at Highland Wildlife Park were considered to represent a range of genetic purity.

"The recent development of a DNA test by RZSS allows us to distinguish those with a high level of hybridisation, who have been neutered and are now part of education programmes at zoos around the UK; and those that are of high purity that will be used in the future breeding programme to conserve the species."