A judge investigating the Dublin and Monaghan bombings has received a quantity of files and information from the British authorities, the Taoiseach Mr Ahern said this evening.
The details should allow Mr Justice Henry Barron to provide an interim report by the autumn into the 1974 attacks which killed 33 men and women, Mr Ahern said.
Bereaved families and victims of the attacks have been lobbying for months for Britain to hand over security documents to the inquiry.
They accused Britain of stalling on co-operation, fuelling their suspicion that British security services colluded with loyalist bombers to plant the devices on May 17th, 1974.
But during Taoiseach's Question Time in the Dáil today, Mr Ahern said a large quantity of documents had now been handed over which would allow Justice Barron to produce an interim report.
However, a preliminary trawl of the documents by the judge suggested that more papers were still needed.
Mr Ahern told the Dáil: "On the issue of Justice Barron I understand he did receive an enormous amount of information, data and files. Whether that will resolve a lot of issues I do not know.
"Certainly he has received the information he asked for and a lot of the records and from that he has highlighted areas where there are gaps and where he wants further information.
"But he is receiving co-operation and there are direct lines of assistance there that were not there.
"That has allowed him to move on very quickly and very speedily to bring us his interim report on the other side of summer," he said.
A spokeswoman for Justice For The Forgotten - the pressure group which has been calling for the hand over of the documents - tonight reacted with "alarm" to the news that Judge Barron would publish an interim report by the autumn.
"That would really alarm us, that would absolutely alarm us because we have heard nothing about an interim report. We are looking for a final report by the autumn," she said.
She went on: "As far as we know they have handed over some documents but Justice Barron now has to go back and make more specific requests."
Meanwhile, families of the victims of the Dublin and Monaghan bombings reacted angrily today to news that the forthcoming General Election could be held on May 17th, the anniversary of the atrocities.