Up to 150,000 students could miss out on a place at university in the UK this year according to the head of the university admissions service UCAS.

Mary Curnock Cook, chief executive of UCAS, also said that up to 70,000 students were opting out of the system this year as they felt they did not have the right offer and will re-apply next year.

Figures show that up to 190,000 students are currently fighting for an ever decreasing number of clearing places, up on 142,000 from this time last year. UCAS estimate that this could leave at least 150,000 students without a place and considering their futures with some uncertainty

Nearly 5,000 clearing places have been filled so far after an inauspicious start which saw phone lines jammed due to the huge numbers of calls from students eager to secure a place. UCAS counted 1.5 million hits to its website and answered many thousands more phone calls from concerned students. But with only 18,000 clearing places available in total, some simple arithmetic shows the numbers of students that may have to miss out.

The number of students opting out of the system this year may provide some relief as many with good qualifications but not necessarily the right offer postpone their applications for another year in order to get on the course they want at the right institution. Although the effect this will have on next year’s rush for places is easy to imagine.

There are also concerns that the high numbers of students opting out is due to the belief that many courses are not worth the effort or the cost. With the average student debt after graduation now standing at £25,000 many students have to seriously consider whether any place is better than none at all.

National Union of Students president Aaron Porter warned that those who have opted to defer application have no guarantee that the situation will be any better next year. Porter said: “They are being encouraged by ministers to re-apply next year but can be offered no assurance in return that there will be a resolution to the annual places crisis.”

Many, such as Professor Les Ebdon, chair of university think-tank Million+, feel the situation is compounded by the fact that many universities may not even be full. With government restrictions on the number of places they can offer and fines for universities over-recruiting, many aspiring students may be left without a place despite there being places technically available.