More than 800 square miles in the Highlands are now safe for wildcats, a conservation project has said.

The Wildcat Haven project has expanded its protection area in Ardnamurchan, Sunart, Morvern and Moidart by 300 square miles.

The project has also carried out "intensive" feral and domestic cat neutering, working with landowners and residents to humanely remove the threat of wildcats cross-mating with domestic felines, known as hybridisation.

Chief scientist on the project, Dr Paul O'Donoghue, said: "The wildcat is a very capable survivor and prefers to breed with other wildcats but it's so outnumbered by domestic cats that hybridisation is inevitable.

"This means that over a few generations those wildcat genes are lost and you're just left with domestic and feral cats causing big problems for prey species and themselves.

"Domestics are basically desert cats and, unless they're curled by a warm fire every night, they live a miserable existence in the Scottish Highlands."

Working in the worst of the Highlands weather and across rough ground, the team has neutered more than 100 cats in the last year, leaving almost 800 square miles where the entire domestic cat population is neutered, allowing the wildcats to begin rebuilding their population.

Mr O'Donoghue added: "A lot of people were saying ten years ago it just wasn't possible to remove the domestic cat threat but we've shown it can be done.

"Our first peninsula, 200-square mile Ardnamurchan, hasn't had a report of an intact feral or domestic cat in three years now; soon the only cats left will be neutered pets and farm mousers."

The news follows an endorsement from Humane Society International (HSI) UK, which has sponsored the project to support its "exceptional" animal welfare standards and humane domestic cat control.

HSI UK executive director Claire Bass said: "This is a fantastic example of compassionate conservation in action.

"Saving this endangered species is of course a fantastic goal but we’re equally inspired and impressed by the positive impact this work has for feral and domestic cats, humanely stopping uncontrolled breeding into a harsh environment, stopping disease transmission, and promoting responsible pet ownership.

Wildcat Haven is providing a humane and effective conservation solution, instead of reaching to the gun or poison to remove feral cats, or imprisoning the last remaining wildcats in zoos."

The project is now looking to expand as far as Fort William and open up further Haven regions in the west Highlands.

Mr O'Donoghue said: "Eight hundred square miles can home around 100 true Scottish wildcats but our aim is a 7000 square mile threat-free area that could hold a sustainable population and save them from extinction.

"Wildcat Haven is living proof that the Scottish wildcat can and must be saved in the wild where they belong."