Significant cuts to college budgets have led to class sizes of up to 100 students and fewer courses for part-time learners, college principals have told the Scottish Parliament.

Speaking in front of the chamber’s Public Audit Committee last week, Margaret Munckton, acting principal of Perth College, said that making class sizes bigger was “absolutely key” to the college balancing its books. “We now are using lecture theatres to deliver theory to 100 students at a time, and then splitting them into groups of 20 for practical,” she said.

She added that although the college would not exceed health and safety limits, “we are doing our level best to increase that average class size, without it being at the expense of quality”.

Susan Walsh, principal of Glasgow Clyde College, also said that class sizes were liable to be increased, but not beyond a point where they were manageable for staff.

Both Ms Walsh and Audrey Cumberford, principal of West College Scotland, said that student enrolment had fallen since 2009-10, predominantly among the over-25s. This has been put down to the Scottish government prioritising full-time courses over part-time ones. Ms Cumberford said: “At West College Scotland, over the period mentioned there has been a reduction in enrolments of 10,000. There has been a reduction in the range of provision we can provide.”

Ms Walsh added that the number of courses offered in the evenings had been reduced. “As a response to the budget cuts, we have looked at trying to concentrate the facility use, and that has led to a reduction in access in the evening,” she said. “So that does make it harder for people in full-time employment to up-skill.”

Ms Walsh and Ms Cumberford said they expected a further reduction in staff in the coming year, on top of the hundreds of teaching and support staff who had already left, although on a smaller scale.

The principals also stressed that tight budgets would restrict the provision to school students recommended by the interim report of the Wood Commission for Developing Scotland’s Young Workforce. Colleges had to play a key role in responding to the report and were willing to do so, but extra resources were needed for them to be able to deliver, Ms Cumberford said.

Meanwhile, Ms Walsh said that, despite their difficult circumstances, colleges were still effectively adjusting their provision to meet demand.

Robert Foster, NUS Scotland vice-president for education, said: “Although we welcome reports that the quality of education in Scotland’s colleges is improving, it is certainly concerning to hear that some colleges are potentially seeing a big drop in students taking part-time courses.

“NUS Scotland has long argued that college regionalisation can result in positive outcomes for students, but only if it does not result in the exclusion of those more likely to take part-time courses, such as mature, female and disabled students.”

Larry Flanagan, general secretary of teaching union EIS, said the challenges of recent years had put a great deal of pressure on lecturers, and other staff, to achieve more with less.

He added that although lecturers would continue to do all they could to ensure quality provision for students, this would become increasingly challenging as funding cuts continued and class sizes rose. “The real solution is enhanced investment in the FE sector, to ensure that learners of all backgrounds and in all parts of the country can have access to a wide range of quality learning opportunities,” Mr Flanagan said.

A Scottish government spokesman said: “Colleges are responding very positively to a demanding reform agenda that places a strong emphasis on courses that help people develop the skills employers need, and principals themselves have made clear the improvements in quality.”