Implementing plans announced by the Progressive Democrats at the weekend to use schools for childcare would be "fraught with difficulty", according to the Irish National Teachers' Organisation.
Under the PD plan, a new childcare programme would cater for primary school-going children using some of the 3,280 school buildings in the State.
The strategy, prepared by Senator John Minihan, suggests that school premises be provided free of charge by the State to groups of parents wishing to set up childcare services.
The facilities would be staffed by a combination of volunteers and professionals and would cost parents €400 a year and €150 for social welfare recipients.
The plans yesterday received a mixed reaction from teachers' unions and parents' groups.
John Carr, general secretary of the INTO, said that while the plans appeared to be an "eye-catching and vote-winning" proposal, there were significant barriers to using schools out of normal hours.
"There is the issue of insurance; who manages the school out of hours; split shifts for childcare workers; asking cleaners to come into school later in the evening," he said.
"Many schools wouldn't have the facilities for after-hours care. You would nearly need to purpose-build childcare facilities on to schools, with kitchens or sports halls."
The Department of Education does not own the vast majority of primary schools. Most are owned by the religious and it would be up to their trustees and boards of management to decide whether facilities could be used outside school hours.
The Catholic Primary School Managers' Association (CPSMA), which represents more than 3,000 Catholic primary schools, said it did not have any objection to the plans, although significant issues remained to be resolved.
Fr Dan O'Connor, general secretary of the CPSMA, said a number of after-hours childcare programmes were already operating in disadvantaged areas of Dublin.
The schools tend to run from 8am to 5pm and offer breakfast clubs, homework clubs and other activities.
Expanding these schemes to other areas would include resolving a number of issues relating to responsibility and funding.
"It would be up to each board of management and each set of trustees to make a decision on the issue. There may be a need to get a sponsoring company other than board of management to be responsible for the use of the school during these hours," Fr O'Connor said.
A spokeswoman for Minister for Education Mary Hanafin said the out-of-hours childcare proposal had been under consideration for a while by an interdepartmental group on childcare and by the National Economic and Social Forum's committee on early childhood education and care.
She said the department encouraged schools to make their facilities available to local community groups outside of school hours and had issued a circular to trustees, boards of management and principals of primary and voluntary secondary schools last month urging them to do so.
The body representing the parents of primary school pupils welcomed the plans and said it supported use of schools outside normal hours for childcare.
