In an attack found to have involved collusion by the British state, 39-year-old Finucane was shot 14 times by members of the Ulster Defence Association (UDA) in front of his wife and three children at his Belfast home in 1989.

The Council of Europe said it would "supervise the ongoing measures" taken by the UK to address the lack of a proper investigation into Finucane's murder, and called on Northern Ireland's Police Ombudsman to provide an update.

The UK's Northern Ireland Secretary Brandon Lewis told Parliament in December he had "considered" a public inquiry into the murder, but had chosen not to pursue one "at this time" and would instead allow the Ombudsman to continue its own review.

The murdered solicitor's son John Finucane, a Sinn Fein MP for Belfast North, said on Friday that the Council of Europe's move was a "hugely significant" step so that the "truth can finally emerge."

During the Troubles, Finucane represented both loyalist and republican paramilitaries, including the IRA hunger striker and MP Bobby Sands.

A British government inquiry published in 2003 found that the state had colluded with loyalist paramilitaries in Northern Ireland, and that there was also a willful failure to keep records, and an "absence of accountability."

Sir John Stevens, who led the inquiry, concluded in his report that collusion between the British security forces and loyalist paramilitaries had taken place in Finucane's murder and that of another man, 19-year-old student Brian Adam Lambert, two years earlier.