A record one in four university applicants were given a controversial "conditional unconditional" offer this year, official figures show.
But despite a significant hike in these offers, would-be students are now less likely to accept them, according to data published by the university admissions service Ucas.
There has been a growing backlash against the use of "conditional unconditional" offers – in which a student is given a place at a university, regardless of the A-level grades they achieve, on the condition they make the institution their firm first choice.
The practice has prompted concern from ministers and school leaders alike, amid warnings they could lead to sixth-formers taking their foot off the pedal during their studies – causing the schools to miss their targets.
Ucas said applicants holding a firm unconditional offer are more likely to miss their predicted A level results, with 57 per cent of applicants missing out by three or more grades, compared with 43 per cent of those holding a conditional firm offer.
The latest Ucas figures show about a quarter (25.1 per cent) of 18-year-old university applicants from England, Wales and Northern Ireland – some 64,825 students – received a "conditional unconditional" offer in 2019, up 4.2 percentage points from 20.9 per cent (53,355 students) in 2018.
Five years ago, in 2014, just 3.1 per cent of applicants received such an offer.
A breakdown by subject shows communications and media has the highest proportion of "conditional unconditional" offers (15.5 per cent), followed by humanities and liberal arts (13.6 per cent).
The Association of School and College Leaders (ASCL) has said the offers are not in the best interests of students.
But university leaders say there are "clear benefits" to institutions using a "variety of offer-making practices", so long as these are used "appropriately and proportionately".
Geoff Barton, ASCL general secretary, said: "It is infuriating that universities have apparently responded to calls to end the use of certain types of unconditional offers by making more of them.
"There are circumstances in which unconditional offers are appropriate, but not when the offer is made on condition that the student makes the university their firm choice.
"This practice has more to do with the frenetic scramble to put 'bums on seats' than the best interests of students.
"It results in many young people taking their foot off the pedal in their A levels, doing less well than they should and potentially damaging their future employment prospects."
Ucas' figures show that while more of these offers are being made, fewer students are opting to take one up.
Overall, among applicants holding five offers of places from universities, including one "conditional unconditional" offer, just over one in five (20.6 per cent) chose to accept the "conditional unconditional" place. This is down from 25.6 per cent in 2014, Ucas said.
Clare Marchant, Ucas chief executive, said: "Students are considering their offers more carefully than ever, with the type of offer they receive having less of an impact than before.
"Our advice to students is to always think about what's most important for them when deciding which offers to accept.
"Unconditional offers remain a complex issue and our new insight will further inform the dialogue, forming a crucial contribution to the current admissions practice reviews.
"Their impact on attainment needs to be highlighted, though this must be seen alongside their role in widening participation activities and benefits to students' mental health."
Education secretary Gavin Williamson has previously condemned the use of "conditional unconditional" offers, saying there is no place for them, and they can limit disadvantaged teenagers from going to the "very best academic institutions" possible.