University lecturers say colleges' revenue is likely to collapse in the year ahead - and they believe the government may need to bail out the sector.
The third-level sector relies heavily on fees paid by overseas students to fund education.
But the Irish Federation of University Teachers is warning far fewer of them are likely to start new courses in September.
The union's general secretary Joan Donergan says it amounts to a "financial crisis".
"The intake in foreign students, which accounts for one-tenth of the student population, that's going to be affected," she said adding that there will also be a decrease in research projects, people doing summer courses and the revenue from student accommodation.