Universities which use ‘unethical’ methods to lure students to take up places have been warned to stamp out the practice.
The Education Secretary is due to write to 23 universities that use "conditional unconditional" offers urging them to end the practice.
A "conditional unconditional" offer is a guaranteed place - but only if students put the university as their first option.
Damian Hinds fears this could ‘trap’ students and prevent them from exploring other options that could be more suitable.
Government officials have now warned that the practice could breach consumer protection laws.
The Department for Education says the laws are designed to protect consumers from entering into a transaction they otherwise would not have.
Mr Hinds is calling for a review of university admissions procedures to look at these kind of offers.
Data also shows that students who accept unconditional offers were proportionally 7 per cent more likely to miss their predicted A levels by two grades than students with conditional offers, the department added.
Mr Hinds will ask the Office for Students (OfS) to take a "comprehensive look" at university admissions procedures.
He also wants the regulator to look at ways of improving current practices, including greater access for students from underrepresented groups and disadvantaged backgrounds.
"I am concerned about the wider picture of how some universities are getting students through their doors, so I am asking the OfS to look at how well current admissions practices serve students and how they can be improved, so we can protect the integrity of our higher education system," Mr Hinds said.
A UCAS report found that while no "conditional unconditional" offers were detected in 2013 providers made 66,315 such offers in 2018.
Over the same period the proportion of 18-year-olds from England, Northern Ireland and Wales receiving a form of unconditional offer rose from 1.1% to 34.4%, according to the DfE.
In his letter to the 23 universities Mr Hinds will say they are "backing students into a corner" to accept a place at their institution and trapping them from exploring other options.
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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."
Ucas Chief executive Clare Marchant said any recommendations must put students' interests first.
"Students' best interests must be the paramount consideration for universities and colleges when making offers," she said.
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