The RSPB has dismissed claims that 22 birds of prey found dead in the Highlands were accidentally poisoned as “misguided and foolish”.
Post-mortem examinations on the red kites and buzzards discovered on land near Conon Bridge since March 18 have revealed the at least 14 were poisoned.
The killings sparked public outrage and the creation of reward fund which has now topped £27,000.
Police, who have searched land and farms in the area, have refused to name the substance involved as the criminal investigation remains ongoing.
There has been speculation that the birds were accidentally poisoned by contaminated carcasses provided by the RSPB.
One Ross-shire farmer, who asked to remain anonymous, said he believed the birds were fed sheep carcasses containing legal treatments used to prevent fluke which can be toxic to birds.
He said: “Sheep are dozed with a drug to kill off fluke and red kites are susceptible to the that poison.
“If the stuff is still in the sheep’s system when it dies and the kites go into the stomach contents and eat it will pass into them undiluted.”
Yesterday, the RSPB vehemently denied the claims.
Duncan Orr-Ewing, head of species and habitats at RSPB, said: “It is misguided and foolish to suggest that the recent incident involving the killing of 22 red kites and buzzards in Ross-shire may have been caused by accidental poisoning of contaminated meat perhaps from a red kite feeding station, road kill or dead livestock.
“If further clarification is needed, most of the red kites and buzzards that have been found dead by the authorities have already been confirmed to have been illegally poisoned by Scottish Government testing at the Scottish Advice and Science for Agriculture laboratory in Edinburgh.”
He said illegal poisoning and other forms of human persecution of birds of prey was a serious conservation issue which is damaging to Scotland’s reputation.
A police spokesman said he was unable to confirm or deny if accidental poisoning had been ruled out but stressed that 14 of the birds had been found to be “illegally” poisoned.
He said he could not comment further due to the ongoing investigation and that inquiries into the deaths were continuing.