The British Government is to face a legal challenge over its failure to launch a public inquiry into security force collusion in the murder of Northern Ireland solicitor Pat Finucane, it has emerged.
Relatives of the Belfast solicitor are to seek a judicial review of David Cameron's decision that Sir Desmond de Silva QC should instead review the papers on the case.
Mr Finucane's widow Geraldine stormed out of Downing Street when informed of the Government plan in October and has now confirmed her intention to launch a challenge in the High Court in Belfast next week.
Secretary of State Owen Paterson apologised at Westminster for the state's collusion in the 1989 killing in which Mr Finucane was shot 14 times by gunmen from the loyalist Ulster Defence Association (UDA) in front of his wife and three children.
During talks on the peace process in 2001 the government of the day entered into an agreement with the Irish government to hold inquiries into allegations that their respective security forces were linked to a number of notorious murder cases, including the Finucane killing.
The Finucane family said that having considered their options, they were now to mount a legal challenge.
Ms Finucane said: "Not for the first time have we had to resort to legal proceedings to vindicate our legal rights.
"It is clear that the British Government have cynically reneged on the commitment made.
"The Cameron decision is also incompatible with Article 2 of the European Convention on Human Rights (the right to life).
"We take the view that the decision not to hold a public judicial inquiry is just another obstacle which we will have to overcome.
"We are determined to get to the truth surrounding my husband's murder. Our campaign will continue."
The legal papers will be lodged in the High Court within days and a date for hearing will be sought.
In the wake of the Weston Park talks, it was eventually agreed that the Westminster government would conduct inquiries into four cases, while the Irish government would hold one inquiry.
All have been held, except the proposed probe into the Finucane case.
It is now known that many of those involved in the murder were agents of the state, but the family has said they want to find out who sanctioned the killing and to expose the full extent of the plot.
Mr Finucane was 39 when he was shot 14 times by the UDA gunmen as he was eating dinner.
His family have campaigned for a full public inquiry since the attack, and his widow has said she felt insulted after Mr Cameron proposed the QC-led review of her husband's death.
Given Mr Finucane's high-profile status as a lawyer who had successfully represented clients facing allegations of IRA activity, the claims of a security force role in the murder quickly emerged.
Retired Canadian judge Peter Cory, asked by the British and Irish governments to examine the allegations of collusion following the Weston Park deal, recommended a public inquiry into the death.
A separate report by former Met commissioner Lord John Stevens in 2003 also said there was collusion.