Europe's leading human rights body is to re-open its examination of the case of murdered Belfast solicitor Pat Finucane.
In November last year the British government again ruled out an immediate pubic inquiry into one of the most controversial killings of the Troubles.
The 39-year-old was shot 14 times by loyalist gunmen as he was having Sunday dinner with his wife and three young children in their north Belfast home in February 1989.
The Council of Europe has announced that it is to re-open its supervision of the case.
It will monitor how the UK addresses the fact that there has not been an adequate investigation into the murder.
One of the solicitor's sons, Sinn Féin's North Belfast MP John Finucane, has descried the decision as "a hugely significant move".
In a tweet, he added: "The British govt have been criticised internationally for their failure to establish an inquiry & this level of scrutiny is vital to ensure truth can finally emerge."
Minister for Foreign Affairs Simon Coveney has also welcomed the decision, describing it as "entirely appropriate".
In a statement, he reiterated the Irish government's "consistent and firmly held position" that there should be a full and independent public inquiry.
He added: "This will facilitate full and thorough scrutiny of the steps to be taken in the period ahead, and to ensure that an inquiry that meets the United Kingdom's obligations under Article 2 of the Convention is carried out.
"The Finucane family, like so many families, has been waiting for too long."
Three independent reports have concluded there was collusion between the loyalist killers and members of the British security forces.
Mr Finucane's family has said only a full public inquiry can reveal the full truth about the extent of that collusion.
But the British government has consistently refused to hold such an inquiry.
In 2019, the UK Supreme Court found that there had not been an investigation into the murder of Pat Finucane that was compliant with Article 2 of the European Convention of Human Rights.
In a statement, the Council of Europe said it had decided to reopen the case "in order to supervise the ongoing measures to ensure that they are adequate, sufficient and proceed in a timely manner".
It has asked the UK to clarify how ongoing reviews of the killing by the PSNI and Police Ombudsman for Northern Ireland "will proceed promptly and in line with Convention standards".
Amnesty International UK Northern Ireland programme director Patrick Corrigan has also welcomed the decision.
"Given the failure to properly investigate this killing, previously identified by the European Court of Human Rights and the UK Supreme Court, it is appalling that the government continues to shirk not only their duty to the Finucane family but also their obligations under international law," he said.
