Sensitive files on one of the most high-profile murders during the Troubles must be handed over to investigators immediately, opposition parties in the Republic demanded last night.

The British security service M15 was prepared in 2005 to hand over files on Pat Finucane, the well-known civil rights and defence lawyer who was murdered in front of his wife and three young children in 1989, according to US embassy cables passed to WikiLeaks.

Taoiseach Brian Cowen reiterated the Irish government's request for a full inquiry into the murder and welcomed what he described as "further work" being done by the British government.

"I understand the British government have been in touch with the Finucane family, that representations have been made and that there is a process under way at the moment and that the Northern Ireland Secretary of State has been involved in that and we await the outcome of that.

"From our point of view, we've always been supportive of the family's efforts to obtain a truthful outcome of the circumstances of that death. We await the recent developments and see what emerges from it," he said.

Fine Gael's former justice and Northern Ireland spokesman Charles Flanagan, who previously raised the case in the Dail and with Westminster officials, said there were more documents in existence than previously admitted. All of these, he said, must now be made available to investigating authorities.

Mr Finucane was shot 14 times in front of his wife and young children in February 1989 by loyalist paramilitaries.

There have been persistent allegations of involvement by security services.

And Mr Flanagan claimed that M15 had never apologised for any of its "misdeeds or collusion" or accounted for what it did during the years of conflict. "That must now change," he said.

He hoped the truth would now finally be uncovered in the case of Mr Finucane.

Labour senator Ivana Bacik said Mr Finucane's case was one which deserved "greater investigation". She is supporting calls for the Northern Secretary Owen Paterson to announce a hearing into the murder in the New Year.

Ms Bacik said it could be a more "contained inquiry" than those previously held -- proving less costly and shorter.

Labour's foreign affairs spokesman Michael D Higgins said the documents into Mr Finucane's murder must be made available "without conditions attached".

The latest round of WikiLeaks' documents revealed that MI5 offered to hand over files during a meeting in 2005.

The son of Mr Finucane, Michael Finucane, welcomed news of that offer as "highly significant".

The family has been calling for a fully independent inquiry, similar to the Bloody Sunday inquiry, into the killing amid claims of collusion between the Ulster Freedom Fighters and members of the security forces.

"We are considering what has been published," Mr Finucane's son Michael told the Irish Independent.

"The fact that M15 has confirmed it holds papers on my father's case is significant.

"Up until now they have denied they had information or taken the line that they won't comment."