Republicans have contributed "absolutely nothing" to the truth behind the Kingsmills Massacre over almost ten years of inquest hearings - and kept their "absolutely vile secrets to themselves", Danny Kennedy has said.

The former Newry and Armagh UUP MLA was speaking yesterday in Dungannon after final submissions to the legacy inquest into the 1976 massacre.

The IRA gunned down ten Protestant workmen on their way home from work in what the Historical Enquiries Team concluded it a purely "sectarian" attack at Kingsmills in south Armagh.

Mr Kennedy affirmed on observation by Coroner Brian Sherrard yesterday about the failure of republicans to assist the inquest since repeated appeals by the inquest for information began in 2014.

Mr Sherrard said through the proceedings there had been an “absence of any assistance from those purporting to represent the IRA or indeed the wider political republican movement concerning this matter”.

Neither Sinn Fein nor the IRA ever accepted responsibility for the attack, however the weapons used had extensive IRA histories.

Mr Kennedy said there had been "very open failings on behalf of the Republican movement for the lack of information or respect or dignity that they've shown in this case.”

"While Republicans have sought a form of justice for their own side and for their own perceived victims and made much of that, they have contributed absolutely nothing to establishing the truth behind Kingsmills. They have kept their dirty secrets - their absolutely vile secrets - to themselves. And that is a reflection of the Republican movement, who and what they are and what they represent."

He has previously said that the experience of many unionists in south Armagh was that “the IRA had a dedicated campaign to remove them... whether you want to call it ethnic cleansing or genocide”.

Mr Kennedy said that the inquest had effectively been "a 10 year process", having begun preliminary hearings in 2014 when requests for a Garda witness began.

The largest adjournment, it was pointed out in court yesterday, was due to delays in securing a Garda witness to give evidence about the attack.

The Republic was used by the gunmen as a base for planning the attack and as a safe haven afterwards, and most of the forensic evidence was captured there.

In March last year a Garda witness finally gave evidence about the massacre - but behind closed doors in a secret hearing in Dublin which the Kingsmills families, their lawyers and the media were barred from.

Barry O'Donnell, solicitor for Karen Armstrong, whose brother John McConville was one of those murdered, and Alan Black, who survived 18 bullet wounds in the attack, said open justice had been damaged.

He said his clients were "really disappointed" that they were unable to participate in the hearing.

While they were allowed to submit questions in advance to the Coroner, these were later presented to the Garda witness behind closed doors.

He noted that the format of the hearing was "a matter for the Government of the Republic of Ireland, as they chose the legislative framework, and they chose not to allow the families to participate".

Only the Irish government can explain why they chose to do that, he said.

But he said the result was clearly at odds with the principle of open justice.

"I would certainly agree with that. Inquests need to be open. Open justice has been the hallmark of how inquests are conducted and without that open justice, rumour speculation can exist."

He also said the secret Dublin hearing could set a concerning precedent for any future engagement by the Irish authorities on Troubles legacy inquiries.

"It certainly could. And that is something for the Irish government to consider."

He asked if Irish authorities would allow victims to participate in such hearings in future.

"Because of the hurt that it caused to our families - I think they need to take cognisance of that, and they need to realise that in order for justice to be seen to be done, people need to participate."

The secret nature of the hearing has left his clients with a "great lack of confidence in the way that was conducted" he added.