A former ASTI treasurer has been accused of filing bogus expense claims in a move that could reopen old divisions within the union.
Mr Michael Ward is understood to have recently received a letter from the union informing him that he was being formally accused of making incorrect expense returns.
Mr Ward, a highly respected figure within the deeply divided union, is to vehemently deny any wrongdoing.
He is being investigated by current ASTI treasurer, Ms Patricia Wroe, under rule 104 of the ASTI's regulations, and faces being charged with bringing the union into disrepute.
The alleged irregularities are believed to centre around expense claims made by Mr Ward which were over and above his Dublin allowance. These claims are said to contravene ASTI rules.
He subsequently made an emotional speech in a private session at last week's ASTI annual conference in Killarney, in which he strongly defended himself against the accusations.
Mr Ward served as ASTI treasurer for over 20 years and is expected to vigorously contest any accusations made against him.
The news that Ms Wroe is investigating Mr Ward will come as a blow to hopes within the ASTI that the disputes of recent years might be at an end.
Ms Wroe previously led the investigation into similar alleged false expense claims by former ASTI general secretary, Mr Charlie Lennon.
Mr Ward is seen by many within the ASTI as having close links with Mr Lennon.
Mr Lennon, who last year agreed to quit his post after a €200,000 settlement, also strongly denied any wrongdoing on his behalf.
At the ASTI's annual convention in Killarney last week, Ms Wroe was narrowly re-elected to the post of honorary treasurer.
This followed a closely fought contest with former ASTI president, Mr P.J. Sheehy, which Ms Wroe won by just one vote.
Speaking after the election, Ms Wroe told The Irish Times she believed her re-election was an endorsement of the work she had done.
"It means that the good practices I've put in place will continue," she said.
However, yesterday she refused to comment on the situation with Mr Ward, saying that to make a comment would be "entirely inappropriate" while any complaint was being investigated.
All due process must be accorded to all parties concerned, she said.
Sources said that during his time in the treasurer's role, Mr Ward was known for keeping a tight rein on the union's purse-strings.
In a sign of support for Mr Ward within the ASTI, he was recently elected, by a large majority, to its standing committee.