Six human rights organisations have accused the Northern Ireland Office of failing to ensure the protection of the high profile solicitor Rosemary Nelson.

The groups have called on the UK government to carry out a "thorough, impartial and independent" inquiry into her murder last March.

Mrs Nelson was killed by a bomb under her car outside her home in Lurgan, County Armagh.

The call for an independent investigation was made by Amnesty International, British Irish Rights Watch, the Centre for the Independence of Judges and Lawyers of the International Commission of Jurists, the Committee on the Administration of Justice, Human Rights Watch and Lawyers Committee for Human Rights.

The human rights groups said in a statement: "The death of Rosemary Nelson undermined the rule of law and was a serious indictment of the RUC's failure to protect her life."

They also added that the Northern Ireland Office had failed "to ensure the protection of Rosemary Nelson's life".

The UK government immediately dismissed suggestions that there was any 'irregularity' in its handling of the case.

'Investigation inadequate'

The groups have criticised the police investigation into her murder, headed by the deputy chief constable of Norfolk police, Colin Port, as "inadequate".

Mr Port was appointed to head the investigation after Royal Ulster Constabulary Chief Constable Sir Ronnie Flanagan opened the investigation to an English police force and the United States Federal Bureau of Investigatations.

Mr Port's investigation, the groups said, was "limited to the circumstances" of the murder, and would not be able to "address Government responsibility and the crucial issues of impunity and accountability of the RUC".

Dissident loyalists opposed to the Good Friday Agreement have been blamed for Mrs Nelson's murder. No-one has yet been charged.

Drumcree dispute

Before she was killed, Mrs Nelson said she had been the victim of death threats, harassment and intimidation by both the RUC and loyalists.

The human rights organisations based in Belfast, London, Geneva and New York have said that the Northern Ireland Office's response to the threats and her allegations of harassment should be investigated in the light of widespread concern about her safety before her death.

She was well known for representing several leading nationalist causes in the mid-Ulster area.

Her work with the residents of the nationalist Garvaghy Road, who were in dispute with Protestant Orangemen over parades in the County Armagh town of Portadown at Drumcree, was particularly high profile.

Mrs Nelson's husband, Paul, has also called for a fully independent, international investigation and inquiry into the circumstances of her murder to be set up.

The Northern Ireland Office said on Thursday that it had not seen the report and so could not comment on it.

But a spokesman said: "The NIO emphatically refutes any allegation of irresponsibility in regard to its behaviour to Mrs Rosemary Nelson."