Amnesty International has called on all judges in Britain to decline appointments to sit on any inquiry set up under the recently-enacted Inquiries Act - including a planned inquiry into allegations of security force collusion in the murder of Belfast solicitor Pat Finucane.
The campaigning organisation also called for the repeal of the act.
The Amnesty call came days after a similar request to judges from Mr Finucane's widow Geraldine who wrote individually to every senior judge in England, Scotland and Wales earlier this week.
Amnesty UK campaigns director Stephen Bowen said: "By holding an inquiry into the Finucane case under the Inquiries Act 2005, the UK Government is trying to eliminate independent scrutiny of its agents."
He claimed: "Any judge sitting on such an inquiry would be presiding over a sham."
Mr Finucane was murdered in front of his family in their North Belfast home in 1989 by members of the loyalist Ulster Defence Association.
In the years since there have been repeated claims of security force collusion with the killers and retired Canadian judge Peter Cory told the Government in a report published last year there was enough suspicion of collusion to merit a public inquiry.
Canadian Judge Peter Cory, who recommended the inquiry into the UDA killing of Mr Finucane in 1989, also opposes elements of the bill that would permit the British government dictate that what it views as sensitive evidence to be delivered in private.
The Irish Government and the Finucane family also wanted no restrictions on the public element of the inquiry.
Taoiseach Mr Ahern lobbied US President George Bush about the issue during his visit to Washington last month but none the less the British government has decided to resist all such pressure.
Amnesty complains the Inquiries Act means the British government would control any inquiry held under its terms and a final report would be published at the British government's discretion.
They say also that crucial evidence could be omitted from publication at the government's instigation - using the excuse it was in the public interest.
Mr Bowen said the Act, rushed through parliament on the last day before it was dissolved for the election, "undermines the rule of law, the separation of powers and human rights protection".
He added: "It cannot be the foundation for an effective, independent, impartial or thorough judicial inquiry into allegations of serious human rights violations."
Both Judge Cory and Lord Saville who conducted the Bloody Sunday Inquiry, came out against the terms of the Inquiry's Bill when it was before Parliament and said they would not sit on an inquiry set up under its terms.
PA