Irish government files relating to allegations that a former taoiseach was involved in a plot to smuggle arms to Northern Ireland in 1969 have been found.

They had been reported missing on Sunday when the 30 year rule which prevents the release of sensitive State papers expired.

Dr. David Craig, director of the Republic's national archive, said the files were transferred in 1996 for safe keeping but, following further inquiries, the files were located on Tuesday morning.

He said arrangements are now in hand for the urgent examination of the records on the files to determine whether there is any reason why they should not be released for public inspection.

The archivist said said the examination should be complete within a matter of days.

The Irish government came under pressure to explain the disappearance of the files which related to meetings of the Irish government in 1969.

At the time, there was intense political pressure in the Republic to come to the aid of Northern Catholics who were being attacked by loyalist mobs intent on burning them out of their homes in areas of Belfast and Londonderry.

Subsequently the then finance minister Charles Haughey and cabinet colleague Neil Blaney were sacked when it was alleged they were involved in a plot to supply arms to Northern nationalists.

They were both acquitted in the subsequent trial and Mr Haughey went on to become Taoiseach in 1979, succeeding the prime minister who sacked him, Jack Lynch.

Now aged 74, he is currently awaiting trial accused of obstructing the work of a tribunal of inquiry into payments made to politicians.

The files disappearance was noticed when other documents from the period were released under the 30-year rule.

Fine Gael leader and former taoiseach John Bruton had called for a police investigation into the lost documents.

In a statement on Tuesday, a Fine Gael spokesman accused the taoiseach's office of "incredible sloppiness".

"Under the act, all files had to be individually checked so any gap in the files should have been immediately obvious even to a casual reader," he said.