The battered body of Miss Rhodes, a friend of John Lennon, was found in woods near her home near Gyor, 65-miles from Budapest in 2009 - months after Hungarian and British authorities had ruled out foul play.

Her caretaker Csaba Augusztinyi admitted killing her, setting fire to her body and was sentenced to 13 years in prison after an appeal in 2010.

But her sister Judith Majlat told Westminster Coroner's Court at a pre-inquest hearing she believed the Hungarian authorities had covered up the murder investigation to protect a local police officer.

For 12 years the 65-year-old grandmother and former beauty queen had cared for abandoned cats and dogs at a sanctuary funded partly by donations from animal lovers in England and a gift from Yoko Ono.

Mrs Rhodes had been the target of a hate campaign and had clashed with local police while running the Puss in Boots Animal Trust.

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She disappeared in mysterious circumstances in September 2008 and her remains were eventually found more than seven months later.

Ms Majlath, a co-laureate who won the Nobel Peace Prize for work against land mines in 1997, said police initially refused to take the family's concerns seriously after Mrs Rhodes vanished.

She believes Horvath Zollan Peter, the local police officer, had something to do with her death and that it had been "covered up."

Ms Majlath, from Vienna, told the court: 'She had been receiving threats in the months before her death, she had even contacted RTL television station to have an interview over it.

"She had an ongoing court case against a local police man, and a witness said that my sister told her months before the murder that in between the court appearances he said to her 'I will get you eliminated'.

"I have grave suspicions, and am very concerned with this policeman. I think they are doing every thing that they say to cover it up.

"He has a bad reputation, because he is a violent person, everybody is afraid of him."

The coroner, Dr Fiona Wilcox asked: "Are you concerned that he was involved in the death?"

Ms Majlath replied: "Yes. They didn't want a criminal investigation, they said that she [her sister Mrs Rhodes] had simply left Hungary because she had no livelihood or chance to live.

"That is according to the first police report.

'" have heard that originally the man who confessed was supposed to get 5 years for manslaughter."

Augusztinyi had told his trial that he had punched Mrs Rhodes before striking her with an axe handle.

He then set fire to the body using petrol, but the torso and other parts were never recovered from the murder scene.

Dr Wilcox said that forensic examinations of the remains in the UK, revealed that Mrs Rhodes had extensive injuries across her body, which she suffered before she died.

"The forensic anthropologist said that bones had not been properly cleaned and still had gravel from on the scene on them," she said.

"Once they were cleaned they found extensive injuries that she suffered while she was still alive."

The hearing was adjourned until January 2013 while the family take the case to the European Court of human rights in Strasbourg.

The coroner added: "There are details in the confession that do not fully explain how she came to die.

"There are too many inconsistencies in the confession and the forensic report in Hungary.

"This suggests the involvement of other parties in his death."

Mrs Rhodes, whose family left Hungary in the late 1956, rose to fame as a model and actress in London in the 1960s.

She attracted the attention of John Lennon and Yoko Ono, who were looking for an actress to star in a film they were making called Rape, about the intrusion of the camera in everyday life.

Eva married British architect Mark Rhodes. The couple later divorced and she established the sanctuary in 1997 using £150,000 of her own money.