Sir Ian Botham has threatened to sue the RSPB, claiming the charity falsely accused him of illegally killing birds of prey.

Lawyers for the former England cricket captain contacted the organisation following recent comments that it made about him on the BBC.

“I don’t take kindly to being lied about”

Writing in the Mail on Sunday, Sir Ian said: “I was more than a little annoyed when the RSPB accused me on the BBC of illegally killing birds of prey.

“Have they heard of the law of libel? I don’t take kindly to being lied about and my lawyers — who make me look like a pussycat — have written to the RSPB.”

Sir Ian, who fronts You Forgot the Birds, a grassroots campaign by the grouse community that believes the RSPB has lost its way, says the allegations are entirely untrue.

Martin Harper director of conservation at the RSPB, said: “We can confirm that we received a letter from lawyers acting on behalf of You Forgot the Birds.

“Our lawyers have responded and the matter is now in their hands. With that in mind, we do not wish to comment further at this stage.”

This is just the latest in a series of disagreements between Sir Ian and the RSPB, with the cricket star recently blasting the charity organisation for, as he sees it, appearing to be more focused on convictions than conservation and sitting on its hands as endangered species die.

“Slurring gamekeepers as criminals”

The RSPB needs to stop “constantly slurring gamekeepers as criminals,” he said. “They do this because it gives them a class war propaganda line against ‘shooting toffs’ to help whip up donations.”

His Mail on Sunday column also said that the Advertising Standards Authority had written to him to confirm it had instructed the RSPB to withdraw “misleading” advertising claims, including that 90 per cent of its £128million income “goes directly to conservation work”. Sir Ian said the real figure was “closer to 26 per cent”.

Sir Ian, who urged the 1.1million people who have donated to the RSPB to consider demanding their money back, commented: “This means that the regulator considers a claim was not just ‘deceptive’ but also caused people to make decisions they would not otherwise have made.

“If a bank had mis-sold in this way we wouldn’t put up with it. So why should we with a charity?” he added.