A South African charity has refunded €1.5m to the Dutch Postcode Lottery after admitting its campaign to inpregnate rhino horns with poison and dye to make them unpopular with poachers is not working.

Animal protection groups told the NRC earlier this year they had doubts about the effectiveness of the project.

‘We were naive and too enthusiastic in our belief that horn infusion would help,’ Peace Parks Foundation chairman and billionaire Johann Rupert told the Sunday Times. ‘It was a mistake, not misrepresentation.’

The Postcode Lottery has confirmed the repayment and has placed the money in a different account until there is more clarity about what methods do work, the NRC says.

The Postcode Lottery gave €14.4m to the foundation in February. During a gala celebration, prime minister Mark Rutte described horn infusion as the ‘key’ to combating rhino poaching.

The bulk of the donation was earmarked for other anti-poaching methods.