An arson attack which burned down a youth project was the culmination of a prolonged racist campaign of violence, the owner has claimed.

It is the second time arsonists have targeted the Hope Project in St Agnes, Cornwall, in 18 months.

Owner Samuel Farmer, 47, said he has been subjected to intensifying verbal and physical abuse over more than five years, ending in his property being burned down.

Mr Farmer said his life has been endangered by "racist" attackers who have shouted abuse and thrown rocks at him and his young daughter, and spat on the family. He believes racists were also responsible for the earlier arson attack on the project, as well as a brutal attack on a horse, which lost an eye as a result, he said.

Both Mr Farmer and his partner are mixed race, and plan to bring disadvantaged young people to the Beacon, St Agnes. The stunning location boasts a range of landscape protections, including a World Heritage Site classification.

Mr Farmer, originally from Liverpool, claimed police have done "nothing" to protect him, or to investigate, and said he has called dozens of times with complaints of racism.

Police say all crimes are investigated thoroughly, and say only four complaints from Mr Farmer are on file. "I have called the police about 40 times because of racial harassment," Mr Farmer said. "Racists have tried to run me over and they have chased me down the lane and spat on me. Police have repeatedly refused to take my statement. They say I have no evidence."

Mr Farmer said allegations of threatening behaviour have been made against him in the past, but have been proved unfounded.

Investigating officer DC Chris Panther confirmed Sunday morning's fire had been classified as racially aggravated, which means longer sentencing powers are available.

But he said all crimes were investigated equally, "as thoroughly as possible".

He said any calls logged would have been investigated.

"We don't just sweep things like that under the carpet," he said.

DC Panther said fire investigators had confirmed the attack was arson.

He said: "I don't know whether it's because someone doesn't like Mr Farmer or it's because of the colour of his skin, but I'll be following any leads and examining the evidence."

Devon and Cornwall Police's diversity officer, Toby Best, has been appointed to offer support.

Mr Farmer welcomed the racist classification of the crime, saying: "If I die as a result of this abuse, at least people will know why."

He bought the site, which contains a single-storey stable building, an annexe and a caravan, 12 years ago, for £25,000. He wants to offer respite holidays to "urban" children, including those from Camborne, Redruth and Truro, and provide opportunities for arts and rural pursuits such as surfing and pony and llama treks. Mr Farmer, an experienced mountain guide, would work with his partner, Carla Wishart, a special educational needs teacher.

Mr Farmer believes the combination of support and beautiful scenery would help children open up. But he said the project had continually been thwarted by vandalism, and said: "People say they don't want these damaged kids on top of the Beacon, but they would never be left unattended.

"They just need therapeutic space to open up."

Paul Green, team leader of social inclusion at Cornwall Rural Community Council, said the Hope Project had "great potential", because of the "passion" of Mr Farmer and his partner, even despite the difficult funding climate.

But Mr Farmer said: "We're scared that if we build this back up it'll be burned down again. We know it will be."

Mr Farmer, who is currently volunteering with black and minority ethnic organisation Unity Cornwall, is unsure how he could fund a rebuild.

"I've just lost £70,000 with all the kit that was burned down too, and I'm on £40 a week," he said, adding that the building was uninsured because of the high premiums resulting from the previous fire.

Mr Farmer said his partner had suffered panic attacks as a result of the incident, and that the pair were now considering leaving Cornwall. But he called on those who welcome diversity in Cornwall to voice their support. "I don't have a problem with Cornish people at all, but the racist element are making themselves very prominent to me," he said. "Under this Stephen Lawrence cloud it's time for good people to stand up for good things."

Unity Cornwall director Victor Downer called on police to act, saying: "I believe that the attack was racially motivated. This is the second time it has happened in the last 18 months and the police now need to be thorough in investigating further.

"Mr Farmer regularly visits the land. He could have been camping there or been in the caravan – the arsonist wouldn't have known. His life could have been in danger."

It is not the first time a building is alleged to have been targeted on racist grounds in Cornwall. In 2008, a pig's head was mounted on a cross outside Quenchwell Chapel, Truro, which was about to be turned into a Muslim centre.