Conservationists are planning to release captive European wildcats into the Highlands in a final attempt to save the Scottish wildcat from extinction.

The new measures, described by ecologists as a last-ditch effort to save the species, follow an expert report that confirmed the Scottish wildcat was on the verge of becoming genetically extinct, with as few as 30 left in isolated pockets of the Highlands.

“Based on the available information, we consider the wildcat population in Scotland to be no longer viable,” the report from the International Union for Conservation of Nature (IUCN), released on Wednesday, stated.

“The number of wildcats is too small, the hybridisation too far advanced and the population too fragmented. We therefore conclude that it is too late to conserve the wildcat in Scotland as a standalone population.”

Conservation sources said the Scottish government had supported work on a captive breeding and release programme from a new wildcat conservation centre being built at the Royal Zoological Society of Scotland’s (RZSS) wildlife park near Kingussie in the Cairngorms.

Ecologists believe they will need to import wildcats trapped on the continent, perhaps as early as next year, and add them to the captive population to help strengthen the gene pool. There are 94 Scottish pure wildcats in captivity and European wildcats will need time to acclimatise to Scotland’s wetter and colder climate.

In about five years, they would be released into an area such as the Cairngorms, but only after a ruthless programme of neutering and culling of feral domestic cats, and further controls on domestic pets in the area, to protect them from crossbreeding.

Roseanna Cunningham, the Scottish environment secretary, said: “The wildcat is an iconic Scottish species and, as such, I will consider every possible action the Scottish government can take to save it, including an increased focus on captive breeding and reinforcement of the Scottish population with wildcats from elsewhere.”

The IUCN reports says recent genetic testing and population sampling by the RZSS and conservation agencies has confirmed the majority of Scottish wildcats are now interbred with feral domestic cats.

Because the species is so elusive and rare, ecologists are not certain how many survive but estimate the wild population ranges from about 30 to 430 individuals. Sampling between 2015 and 2018 found only 20% were pure wildcats, while 80% were either hybrids or actually entirely domestic.

An RZSS genetics study published last year found, however, that the extent and rate of crossbreeding was so advanced that domestic cat genes were now dominant in the surviving wild population.

The IUCN, which has very strict rules on reintroducing wild species in areas where humans endanger native populations, said any release programme would have to be tightly managed.

“We reason that the recovery of the wildcat in Scotland will only be possible with the support of reintroduction/reinforcement projects, and that the remaining ‘pure Scottish wildcats’ should be combined with wildcats from continental Europe,” its report said.

“Both reintroduction projects or reinforcement of remnant nuclei should be considered. This requires a rigorous suppression of feral cats and hybrids in areas of reinforcements, and the removal of feral cats in areas of potential reintroduction.”

Arriving after the last ice age, wildcats were once widespread across northern parts of the UK mainland and Wales. After 10,000 years of isolation, they are now genetically distinct from European populations but their numbers have plummeted due to habitat loss, disease, human persecution, interbreeding and road deaths.

Even so, the IUCN report recommends the Scottish project should keep in contact with proposals, still in their infancy, to reintroduce wildcats to other parts of the UK.

Dr Andrew Kitchener, chairman of the Scottish Wildcat Action steering group, a coalition of more than 20 agencies and charities, said: “We now have the strongest and most reliable evidence to date that wildcats are in a more endangered state than previously understood.

“While we believe there are wildcats remaining in the wild in Scotland, there are no longer enough to ensure their continued survival as viable populations. We can now plan the essential next steps to give the wildcat a sustainable future.”

Eileen Stuart, head of policy with Scottish Natural Heritage, a government conservation agency, said efforts to ensure the survival of the species must involve help from the wider public.

“A key part of this will be a national conversation on domestic pet and feral cat populations and how we manage these,” she said. “The public will have an important role in helping minimise future hybridisation. Responsible cat ownership – including microchipping, neutering and vaccinations – is one way we can help reduce the devastating effects on wildcats.”