Animal rights activists have targeted the parents of Britain's first known human victim of "rabbit flu", with telephone callers telling them his death was a "rabbit's revenge".

John Freeman, aged 29, died after becoming infected with the bacteria pasteurella multocida after picking up a rabbit on his farm.

He fell ill the next day with a fever and died three days later.

His parents Joan and Peter Freeman, who farm at Aspall, near Stowmarket in Suffolk, spoke out following their son's death to appeal for greater awareness of the bacterium that caused his death.

But the couple were horrified when anti-hunting extremists telephoned them within days of their son's funeral and implied their son deserved to die.

Mrs Freeman said on the day they spoke out, extremists had telephoned to tell her that the couple's only child had been "popping off rabbits for fun".

In a separate call, Mr Freeman was told that the death might be "rabbit's revenge".

The couple went to a relative's house to escape the ringing telephone.

"They were implying that my son deserved to die," Mrs Freeman said. "I just can't understand how people can be so callous. To ring someone up who is devastated with grief - it is disgusting."

John Freeman's parents said their son had been a conservationist.

Mrs Freeman said: "I can't believe these people are caring, or nature lovers or conservationists themselves."

A post-mortem showed that Mr Freeman had died from septicaemia after becoming infected with the bacteria that causes pasteurellosis, which is known as rabbit flu or snuffles.

A spokesman for the Health Protection Agency said the bacteria was known to be common among many domestic animals, including cats and dogs, but he was not aware of any other fatal rabbit-to-human transmission.

Mrs Freeman said she believed the bacteria passed into her son's blood stream via a blister he had on his thumb. Mr Freeman died on August 5.