A London university has said it is stopping making unconditional offers to would-be students, to ensure it maintains its entry standards.
St Mary's University, Twickenham, took the decision after discovering some students, given unconditional offers, did not get their predicted grades.
There has been a rise in the number of unconditional offers in recent years, which has drawn criticism.
Universities Minister Sam Gyimah said it undermined the education system.
Last year, nearly a quarter of applicants from England, Wales and Northern Ireland received at least one unconditional offer.
That is where they do not need to achieve certain grades in order to be admitted.
In total 67,915 unconditional offers were made to 18-year-olds in 2018.
The university and college admissions service said the offers were not necessarily being made to the highest-achieving candidates.
Unions said the situation risked encouraging teenagers not to strive for the best A-level results possible.
And Mr Gyimah said giving out unconditional offers just to put "bums on seats" damaged the credibility of the university system.
'Not worth pursuing'
He also said they risked distracting students from the final year of their schooling, and could sway them into making decisions they may not have otherwise made.
John Brewer, Pro Vice Chancellor of St Mary's University said: "We believe that we've made the right decision to withdraw unconditional offers.
"We are determined to maintain standards of entry to St Mary's and by listening to the views of schools, teachers, our own staff and students we believe that with the evidence that has been available to us that we've made the right decision."
He added: "It was clear to us that a number of students who enrolled with us after an unconditional offer was made didn't meet the grades they expected."
People with conditional offers were found to be more likely to achieve their grades.
Last year the university, which has degree entry tariffs ranging from BBB to BBC, made 499 unconditional offers.
It was the first year it made them and the university said the data showed it was not worth pursuing.
Head of policy and campaigns at the University and College Union, Matt Waddup said: "The decision by St Mary's demonstrates the desperate need to overhaul our failing admissions system.
"We are alone in the world in persisting with a system where students are offered university places based on highly inaccurate predicted grades.
"Unconditional offers have made a mockery of exams and led to inflated grade predictions, while putting students under enormous pressure to make a snap decision about their future.
"The simplest and fairest way to deal with these problems is for us to adopt a system of post-qualification admissions, where offers are based on actual achievement rather than estimated potential."