The Deputy General Secretary of the ASTI has said plans to transform Synge Street CBS in Dublin into a Gaelcholáiste are going ahead without proper consultation with staff who are "being kept in the dark".
Speaking on RTÉ's Morning Ireland, Diarmaid de Paor said the biggest problem is how it is being handled.
Mr de Paor said the school, like many inner-city schools, is suffering from dwindling numbers and after some discussion one suggestion was to turn the all-boys school into a co-educational Gaelcholáiste.
He said that parents have not yet been consulted about the change.
"Quite frankly, the teachers have been kept in the dark for the whole of this process, as has the rest of the school community."
He said the Edmund Rice School's Trust (ERST), when asked to examine the feasibility of a Gaelcholáiste "took that and decided that that was a request to move into a Gaelcholáiste and went to the Department and started the ball in motion."
Staff previously said news that the school was converting to a Gaelcholáiste was broken to them just hours before it was publicly announced.
Mr de Paor said ASTI members want this process to be paused and stopped and "brought back to the beginning and done properly".
"Remember that these teachers have been, without any consultation, without any notice, have been basically told their lives are being turned upside down and they'll either have to find another school or, if they can, upskill to Irish," he said.
Mr de Paor said he is not sure that a Gaelcholáiste is suitable for that school as it is envisioned as a 400 student school and the facilities are not adequate.
He said the problem with the change is the way the staff and the school community have been involved in the plans.
"They still haven't talked to the parents at all. The way the staff have been treated is, quite frankly, shameful."
He called for the Department of Education to pause the process to "give some breathing space in this" so discussions can take place and a consultation can result in an agreed outcome with teachers being part of the decision-making.
Read more: What lies ahead now for Synge Street?
The Edmund Rice Schools Trust said in a statement that it met Synge Street CBS's Board of Management last night.
It acknowledged that "staff are understandably disappointed with and feel disrespected by the lack of consultation in the change of status process as well as the speed around which it has taken place".
ERST has informed the board and the staff that an agreement has been reached with the Department that there will be another intake of students taught through English in September 2026, as per the board's recent request to ERST.
It said a Príomhoide Tánaisteach would be appointed to Synge Street CBS to "lead out on the development of the co-educational Gaelcholáiste".
However, to "ensure that the legitimate needs of those awaiting for the Gaelcholáiste are met, there will also be - as planned - an intake of students taught through Gaeilge in September 2026."
It said current teachers would be provided with a "comprehensive upskilling programme" to help them teach in the Gaelcholáiste.
The trust said that "ongoing support and information" will be provided to staff around the "redeployment process" for those who opt not to teach in the Gaelcholáiste.
