More than 60% of posts on teacher supply panels in the Dublin region are vacant, as well as one post in ten across the rest of the country, according to Department of Education figures received by RTÉ News.
The panels were established across the country to ensure a ready supply of substitute teachers to primary schools in their local area, but a significant number of the panels in the Dublin area are either completely empty or significantly understaffed, because of the teacher shortage.
School principals in charge of panels in the Dublin area have told RTÉ News that despite advertising numerous times it has proven impossible to find teachers to take up positions on the panels.
In some cases no applications were received after advertising.
This new data from the Department of Education reveals the scale of the problem across Dublin and the rest of the country.
Out of 183 posts supposed to serve 29 school clusters across county Dublin, just 70 positions are currently filled.
The remaining 113 teaching posts, or 62% of the total, are vacant.
These are all full-time fixed-term teaching positions, but no teachers can be found to take up the posts.
The problem is less acute in other parts of the country, but the data shows that finding teachers remains a problem beyond Dublin too.
The data show that 9% of posts on supply panels across the country outside of Co Dublin are unfilled.
The supply panels were established in recent years and expanded this year in an effort to help schools find substitute teachers at short-notice.
Each panel serves a cluster of schools in its area.
Their establishment was welcomed at the time by schools leaders and teachers.
However, school principals have complained in recent months that many of the panels are not fulfilling their function because they are either empty or significantly understaffed.
In a recent survey of primary school principals 87% said they had ongoing problems finding substitute teachers.
In Dublin that rose to 98% of respondents.
The substitute teacher problem is just one facet of the wider teacher shortage, that school and teacher organisations say is now at crisis levels.
The problem is most acute in Dublin and in neighbouring counties. The high cost of accommodation in and around the capital is being blamed.
The Irish Primary Principals Network found that a quarter of primary schools nationwide were finding it impossible to fill all teaching posts, while in Dublin the proportion rose to two out of every three.
Primary teachers union the INTO said a number of crises were currently affecting the ability of schools, particularly in larger urban areas, to recruit staff onto the panels and to fill other roles including permanent teaching positions.
"The cost-of-living crisis, the lack of housing and massive increases to rents have exacerbated the problems associated with teacher recruitment," General Secretary John Boyle said.
"These issues, coupled with the Department of Education's failure to properly plan for teacher supply, are impacting negatively on primary and special education. Tackling these root causes is the only sure way to deal with the recruitment and retention challenges at primary level".
The union said it contacted the Department of Education last month seeking an urgent meeting about the teacher supply crisis and it is awaiting a response.
President of the Irish Primary Principals Network, Brian O'Doherty, has said that schools are trying to manage the situation with existing resources, but this is not a sustainable solution.
He said that the challenge for principals sourcing external substitute cover for teacher absences is not a new problem, but "does continue to be a significant one".
Speaking on RTÉ's News at One, Mr O'Doherty said: "Given the lack of availability of substitute teachers in schools, they are having to manage the situation from within their own resources and there are really only two practical or workable solutions.
"One is to divide up the class of the absent teacher and spread those children among the other classes in the school, which means that those children are being supervised but not taught, and that's really not a sustainable solution if the absence of the teacher is more than a day or two.
"And then the other is to redeploy a special education teacher to teach the mainstream class and according to our figures, 83% of schools countrywide have had to redeploy a special education teacher, and that has obvious implications for continuity of provision to children with additional needs."
Mr O'Doherty called for the reinstatement of a system where these lost hours of special educational assistance could be "banked". This provision was previously implemented during the pandemic.