A significant number of employers seeking staff are telephoning schools to ask students to work for them, the ASTI conference has been told.
One delegate said there were often not enough students around in the afternoons to make up a football team. Another delegate said the situation in terms of exploitation of young people was the worst since the industrial revolution.
Other delegates said that while some students did not miss classes as a result of their part-time work, they found it difficult to concentrate during lessons.
A Monaghan delegate, Mr Finbar Bohan, said that schools in his area were constantly being rung up by employers in relation to part-time work. "They are telling the students that if they don't come into work now they will lose their weekend or holiday work," he said.
Mr Bohan called on the union leadership to make representations on the issue to the Department of Education and IBEC. "This exploitation has to stop now because the future of these young people is at stake," he said.
Ms Maire Ni Laoire, a Cork delegate, said that the level of part-time working made trying to organise extra-curricular activities extremely difficult. "Such part-time working is lessening students' life chances," she added.
Mr Kevin Brogan, from Drogheda, said that a survey of 295 second-level students in his area had found that 200 of them were working part-time. A lot of this work was unregulated and students were not aware of their rights.
He claimed that many students were working hours which were not permitted under employment legislation. "What happens after 10 o'clock if they are in a kitchen or pub? Or if they fall over? Where is the insurance then?"