The six men, five of whom were unarmed members of the IRA and INLA, died in what had been described as 'shoot to kill' incidents in Co Armagh.
John Leckey, the Belfast coroner, said he could not do his job because of a High Court ruling denying him access to the reports by two senior English policemen, John Stalker and Colin Sampson, who looked into the killings.
Earlier this year Mr Leckey issued a subpoena for the two reports, but it was resisted by the RUC. A High Court judge ruled in July that the reports were not relevant to the coroner's inquiry and should not be produced on grounds of national security. Families of the men killed said they had not received justice and were considering taking a case to the European Court of Human Rights.
Three of the men who died in the first shooting on 11 November 1982 belonged to the IRA. Eugene Toman, James McKerr and John Burns were in a car which was raked by police gunfire outside Lurgan, Co Armagh.
Roddy Carroll and James Grew, both members of the INLA, died when their car was hit in Armagh city a month later.
The sixth victim was a teenager, Michael Tighe, who was shot dead at a hayshed near Lurgan which had been under police surveillance - 13 days after the three IRA men were killed.
Teresa Carroll, the mother of one of the dead men, said: 'I'm very disappointed. It's a cover-up. It just brings the law into further disrepute.
'It just shows there was a shoot to kill, and there must have been something in the Stalker report that they didn't want seen.'
McKerr's sister-in-law Mary Green said all the relatives were deeply disappointed but not surprised by Mr Leckey's decision. 'It is very, very disappointing that after 12 years it should end like this. We are very frustrated and really shattered. We intend to fight on.'
The inquests were held up for years, first by unsuccessful criminal prosecutions of some of the RUC men involved in the incidents and later by legal challenges. A dispute over whether the officers involved could be compelled to give evidence at the inquests went to the House of Lords, which ruled they could not.
Abandoning the inquest into three of the deaths yesterday, Mr Leckey said the High Court ruling refusing him access to the reports meant his aim of fully examining the circumstances surrounding each of the three shootings was 'no longer achievable'.
Tom Hartley, Sinn Fein's national chairman, said the refusal to make the reports available made nonsense of Britain's claims of a just and fair legal system in Northern Ireland. He said it was evidence of the lengths to which the Government had gone to cover up a shoot-to-kill policy.Reuse content