Social mobility experts have warned that government proposals to introduce minimum eligibility requirements for higher education loans in England will hit poorest students hardest, in effect “closing off university prospects at age three” for the most disadvantaged.

On Thursday ministers are expected to outline plans that would prevent pupils from taking out student loans to study at university if they fail maths and English GCSEs, as part of its long-awaited response to the Augar review of post-18 higher education funding.

Proposals to introduce a lifelong loan entitlement (LLE), worth the equivalent of four years of post-18 education to support students to train and study throughout their lives through flexible courses, are also expected to form part of the package of reforms, which are likely to be the subject of a lengthy consultation.

Headlines, however, are likely to focus on any government proposals to limit student numbers and block candidates who fail to pass GCSE maths or English, which many see as a retrograde step to efforts to widen participation in higher education.

Lee Elliot Major, a professor of social mobility at the University of Exeter, warned: “If this is implemented crudely it will effectively be closing off university prospects at age three for many poorer children. Our research shows the depressingly strong link between achieving poorly in early-age tests and failing to get passes in English and maths GCSEs at age 16.

“Children from the lowest fifth of family income backgrounds are five times more likely to leave school without passes in English and maths GCSEs basic skills than those from the highest fifth of incomes,” he added. “We already label a third of pupils taking English and maths GCSEs as failures – this will only condemn them further.”

About 71% of pupils in England achieve a grade 4 in GCSE English and maths, falling to 52% among disadvantaged households. Among English 18-year-olds accepted on university courses, 92% got grade 4 in English and maths in 2020, meaning the 8% who did not might not in future be able to access higher education.

Sir Peter Lampl, the founder and executive chair of the Sutton Trust, warned: “Universities are the key route to social mobility, so it is crucial that young people who have the potential to benefit from higher education are able to do so, whatever their background.

“The introduction of any minimum grade requirement is always going to have the biggest impact on the poorest young people, as they are more likely to have lower grades because of the disadvantages they have faced in their schooling.”

Ryan Shorthouse, the chief executive of the centre-right thinktank Bright Blue and former adviser to the Conservative party on families and education, added: “Restricting access to student loans is not the right way to reduce the government’s subsidy on student loans. It penalises prospective students, disproportionately those from Britain’s poorest families.”

Geoff Barton, the general secretary of the Association of School and College Leaders, said: “Those with the aspiration and commitment to access higher education should be helped to achieve that ambition. To do the opposite smacks of a lack of ambition on the part of the government. It seems more like a case of removing the ladder up, rather than levelling up.”

Other headline measures likely to be announced include the freezing of the tuition fee at £9,250 for another two years, until the end of the current parliament. That will result in an effective cut in university incomes from teaching undergraduates, with the value of the tuition fee already considerably eroded by inflation. In real terms its value by 2024 is likely to be much less than £7,000, depending on the rate of inflation.

The government is also expected to announce a similar freeze on the threshold earnings for student loan repayments, hitting recent graduates who will find themselves having to make higher repayments as their wages rise more quickly above the threshold.