Up to 30,000 fewer students may have started university courses this year following the tuition fee hike, the government's fair access tsar has suggested.
Professor Les Ebdon, director of the Office for Fair Access (OFFA), said fear of higher fees "appears to be an obstacle" for some - particularly for mature students.
He acknowledged that university applications are still be watched "anxiously" to see if the move to triple fees to a maximum of £9,000 will continue to be felt.
Ucas is expected to publish figures on the numbers of students starting degree courses this autumn shortly.
In an interview with Civil Service World Ebdon said: "I think we will find when the numbers come out that probably 20,000 or 30,000 fewer students have started this year than the year before."
He added: "We're all watching the applications anxiously to see whether that's a one-year effect or an ongoing effect."
Asked what obstacles there are to increasing the number of applications from disadvantaged groups of students, Ebdon said that fear of tuition fees "appears to be an obstacle, particularly for mature students who are much more difficult to reach than school leavers.
"They seem to have dropped off," he added.
There has also been a fall in applications from part-time students, Prof Ebdon said.
He insisted that the English fees system does encourage people to go to university, and is "one of the most progressive in the world", but added that there have been problems communicating this.
Figures published by Ucas last week showed that the number of students in England applying to university has slumped by almost 10%.
In total, 107,687 potential university students have already submitted their applications, the figures show, compared to 119,548 who had applied by this point last year.
It means that almost 12,000 fewer people living in England have applied to start degree courses in autumn 2013 - a fall of 9.9% compared to 2012.
Ucas chief executive Mary Curnock Cook has said that changes at this point in the year are "a poor guide to final demand".
The main deadline for applying for degree courses starting next autumn is mid-January.
Students planning to start degree courses next autumn will pay tuition fees of up to £9,000 a year. The hike was introduced this autumn.
A Ucas report published in the summer found that about one in 20 English 18-year-olds - about 15,000 in total - who might have been expected to apply to start university in autumn 2012 did not.
The situation was worse for older applicants - English students over the age of 18 were between 15% and 20% less likely to apply for 2012 than 2011, it said.
Part of the drop may be due to more people accepting places last year, Ucas suggested.
A spokeswoman for the Department for Business, Innovation and Skills (BIS) said: "The Government's reforms have made the university system fairer and more progressive.
"Most new students will not pay upfront, there will be more financial support for those from poorer families, and everyone will make lower loan repayments than they do now once they are in well-paid jobs.
"Our Student Finance Tour which ran in 2011 is being repeated in 2012. Last year it was highly successful in getting the message out to prospective students about the range of support available for university entrants.
"This year we have broadened its scope and recent graduates are now in schools talking to Year 9 and 10 students and their parents, as well as Year 11s preparing for the future."