Dr Roger Mugford, who runs an animal behaviour centre in Surrey, accused the charity of having a "vendetta" when he gave evidence in the case of grandmother Irene Chambers.

Mrs Chambers appeared in court last week after Belfast City Council attempted to have her two dogs, which they believed were pit-bulls, destroyed.

The dogs were later returned to the pensioner - although one had to be put down last night after it attacked the other.

USPCA boss Stephen Philpott hit out at the court's decision to ban a lawyer for Belfast City Council presenting undercover TV footage featuring Dr Mugford.

The magistrate accepted the defence's evidence that the dogs were not pit-bulls and were mongrel types.

The footage - recorded for UTV's 'Insight' - appeared to show the animal psychologist telling an undercover reporter it would be fine for him to class a pit-bull purchased in Finland as a Boxer cross Labrador.

He said on film: "Yes, perfect. Yeah that's all right. That will work."

But he told the court the programme had been "edited outrageously" and said he was intending to initiate legal proceedings against UTV and the USPCA.

He also said it believed it was a "set-up job" by the charity.

The council - which is set to appeal against the court's ruling to return the pets to Mrs Chambers - also expressed its "disappointment" over the decision not to allow the programme as evidence.

Mr Philpott yesterday challenged Dr Mugford to sue the USPCA.

He said: "I would love to get Dr Mugford into a courtroom so that we could challenge his practices and his theories.

"We were deeply disappointed the views he made on the Insight programme were not presented to the court.

"I don't have anything against grannies and the only thing we did was act in the interest of public safety.

"I hope there is an appeal and the footage from the programme can be taken into consideration. We are not worried about this man in the slightest.

"This is a man who claimed pit-bulls get a bad Press and people have to realise this."