Education secretary Damian Hinds has told 23 universities to stop making "conditional unconditional" offers of places.
He said such offers harmed student attainment, damaged the reputation of universities and were potentially unlawful.
Mr Hinds said a full review of university admissions was also needed to end "unacceptable" practices.
"Conditional unconditional" offers guarantee students a place, but only if they put the university concerned as their first option, in effect preventing them from exploring alternatives.
The Department for Education says this could breach consumer protection laws designed to protect people from being pressured to enter into transactions.
Universities' 'pressure-selling tactics'
Mr Hinds said: "It is simply unacceptable for universities to adopt pressure-selling tactics, which are harming students’ grades in order to fill places. It is not what I expect to see from our world-class higher education institutions.
“‘Conditional unconditional’ offers are damaging the reputation of the institutions involved and our world-leading sector as a whole. That is why I will be writing to 23 universities, urging them to stamp out this unethical practice.”
Concerns about wider recruitment practices by universities meant that a review of admissions was needed by the Office for Students (OfS), he added.
The DfE said that in 2018, 34.4 per cent of 18-year-olds from England, Northern Ireland and Wales – equivalent to 87,540 people – received a form of unconditional offer, up from only 1.1 per cent in 2013.
The University of Roehampton made 1,940 conditional unconditional offers, representing 65.8 per cent of all its offers to 18-year-olds.
Ucas data last year showed that students who accepted unconditional offers, whether "conditional" or not, were 7 per cent more likely to miss their predicted A levels by two grades than students with conditional offers.
The OfS in January warned universities that were pressuring students into accepting unconditional offers that they risked being fined or even deregistered.
Ucas chief executive Clare Marchant said: “Last year, Ucas revealed the extent of increases in unconditional offer-making as part of our commitment to transparency in admissions, which now sees us publish nearly 3 million data points each year.
“We welcome the review of admissions practices and look forward to continuing our work with the Office for Students as the review’s scope and remit is shaped. There needs to be a clear objective that any recommendations put the interests of students first, working with teachers, universities and colleges.”
A Universities UK statement said: “There are clear benefits for students in universities being able to use a variety of offer-making practices that reflect the individual student’s circumstances and potential.
“It is essential that admissions processes and policies are fair and transparent, underpinned by clear criteria and in the best interest of students.”
Universities UK said its members must be able to explain why and how they award unconditional offers with conditions attached, and that it was working with Ucas to review guidance.
The universities that Mr Hinds will write to about their use of conditional unconditional offers in the 2018 recruitment cycle are:
- University of Roehampton
- Loughborough College
- Kingston University
- Sheffield Hallam University
- University of Brighton
- Birmingham City University
- Nottingham Trent University
- Bournemouth University
- Staffordshire University
- University of Lincoln
- University of Hertfordshire
- Royal Holloway, University of London
- Oxford Brookes University
- Lancaster University
- University of Birmingham
- Middlesex University
- University of Derby
- University of West London
- City, University of London
- Keele University
- University of Kent
- Aston University, Birmingham
- University of Surrey.
The University of Roehampton told Tes it no longer offers conditional unconditional offers. A spokesperson said: "We revised our process mid-cycle this year and we made the decision to stop 'conditional unconditional' offers for anyone who applied post the 15th January UCAS deadline, and notified UCAS of our position on 8 March 2019."
Providers that have said they will no longer make unconditional offers include:
- St Mary's University, Twickenham
- University of Nottingham
- University of Sussex