Student admissions have risen above 45,000 for the first time, figures due to be released this week will show.

According to a source in the Higher Education Authority (HEA) the figures will show a massive increase in the number of those who have entered higher education in 2009.

They will also detail a substantial rise in those who have entered third level as mature students.

"This year saw the largest ever jump in admissions. Figures are being finalised but the number of first-year students admitted through CAO will top 45,000 for first time, and there has also been significant growth in numbers coming through other access routes, especially mature students returning to education," said the source.

According to Ned Costello of the Irish Universities Association (IUA) the rising number of students in Ireland's third levels is pushing costs up even further amid a worsening financial crisis in colleges.

"We're not in the business of turning students away, but with these numbers rising so high, it means costs are rising while resources are falling."

The figures arrive amid much speculation on upcoming budget cuts for the third-level sector.

One senior university source has said third-level bosses have been told to expect a minimum 10% cut to the grant supplied by the Department of Education. "University heads have been pre-warned that this is one of the measures being considered. This will have serious implications for the survival of some of our colleges," he said.

The current grant supplied is in the region of €1.4bn. The new measure would represent a cut of €140m.

According to a spokesperson for the Department of Education, "All expenditure options are under review. No figures have been put on anything."