The principal of a secondary school in Dublin city fears she may have to close the school on health and safety grounds.
It is due to rubbish not being collected since the start of an indefinite strike by school secretaries and caretakers.
Speaking on RTÉ's Today with Claire Byrne programme, Alexandra Duane from St Joseph's Secondary School in Fairview said she is fearful that rats will be attracted by the uncollected rubbish at the school over the weekend.
"[The school is] already really, really in a bad state, we have a lot of seagulls and birds and everything coming in," she said.
"I'm very fearful that it's going to turn into rats. We're directly across the road from Fairview Park and over the weekend there won't be anybody here.
"I'm very anxious about Monday morning," she said.
Ms Duane said that she will go into the school on Sunday to assess whether or not it is safe to open on Monday morning.
She added the school "fully supports" the striking secretaries and caretakers and that taking on any of their responsibilities would undermine the industrial action.
"The only exception to that is to make sure that people who aren't on full time contracts get paid, so myself and the deputy principal are handling that at the moment.
"But in terms of the daily activities, I completely agree. I think if we started taking on those jobs, we would be undermining everything that they're doing," Ms Duane said.
She added: "The whole point of the strike ... is to show the impact that them not being there is going to have on the school.
"I would sort of jokingly say, 'They're the heart of the school and that the school would fall apart without them'.
"But now it is falling apart without them, and it just shows how important they are."
Ms Duane said that there is also a build-up of child benefit forms that need to be stamped to show that over-16s are still in full time education and that invoices are unable to be paid.
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Concern over delays to payments for substitute teachers
Meanwhile, the principal of St Luke's Primary School in Douglas, Cork said that substitute teachers might not be paid for their work on time because of the strike.
Speaking on the same programme, Olwen Anderson said the school is managing for now, but the situation will become more unsustainable the longer it is allowed to go on for.
"Our secretary coordinates all of the finances of the schools, so organising invoices, accepting those things, that won't happen.
"Deliveries to the school, that's not happening at the moment and then communicating with parents as well is becoming incredibly difficult," she said.
Ms Anderson added that the school supports the caretakers and secretaries in their industrial action.
However, she said the school is disappointed that no progress has been made in talks between the Government and Fórsa.
"We're very concerned that nothing seems to be moving forward and that there's no end date to this in sight."
