Defence Minister Alan Shatter has already ordered an independent inquiry into the case after a witness came forward and undermined the findings of three military investigations.
This review is to be finished by August 19.
Corporal Fintan Heneghan, 28, Private Mannix Armstrong, 26, and Private Tomás Walsh, 30, were blown up by a roadside bomb as they returned from picking up rocks along a remote dirt track in southern Lebanon.
The army and the United Nations have always claimed the road was safe, was authorised for use and that there was no evidence of negligence.
However, pictures have emerged on the internet that show the obvious dangers the men were in on the morning of March 21, 1989.
These pictures, which are published in today’s Irish Examiner for the first time, show the devastation after the blast and the poor state of the track where the mine was buried.
Other UN maps show that the explosion happened well inside a zone controlled by Israeli forces, where peacekeepers were under additional threat.
The army has always argued the threat level was low, particularly with respect to roadside bombs. And it said there was no history of such attacks against personnel of the United Nations Interim Force in Lebanon.
Separate UN documents from the time show that roadside bombs had been used by Lebanese resistance fighters to target and kill peacekeeping soldiers. They also show ongoing concerns of peacekeepers because of mines.
Already this month, the state settled a 21-year-long High Court case with the widow of Private Armstrong in a €300,000 pay-out.
Gráinne Armstrong’s barrister told the High Court her husband and his colleagues were “sitting targets” at a time when the Irish battalion was under specific threat.
The court heard that Ms Armstrong’s case was based on the belief that the army was negligent in not checking the road for mines or warning the men.
The pictures and documents have been supplied to senior counsel Frank Callanan, who has been appointed by Mr Shatter to carry out the review.
It is understood the dramatic twists in the case happened after the testimony of a senior officer serving in Lebanon at the time contradicted the official version of events.
Announcing the inquiry, Mr Shatter said that had this evidence been available to previous inquiries, they may have reached different conclusions.
These inquiries — an army board of inquiry and UN board of inquiry in 1991 and an internal army review in 2003 — decided that there was no evidence of negligence on behalf of commanding officers.
A spokesman for the families and Corporal Heneghan’s brother, Enda Heneghan, said he hoped the fact that the inquiry had been called would lead to answers.
“Certainly, I believe this was a cover up and if there was such behaviour in any other area [other than the army] the consequences would be quite severe.
“If [the result] is as we looked for, and fought for, and talked about for 22 years, and the inquiry finds, [then] this it is really quite damning,” he said.
The army said that all queries in relation to this issue are being dealt with by the Department of Justice. The department said in a statement that it would not comment until the inquiry is published.
The families have already supplied 10 witnesses and substantial additional information.
Interviews are ongoing and Mr Callanan is due to deliver a report to Mr Shatter on August 19.