It could take more than three centuries to close the gap between the richest and poorest students at highly selective universities, a report has suggested.

Progress in narrowing the gap between the most and least advantaged students being admitted onto undergraduate courses has slowed in recent years, according to an analysis from the universities admissions service.

Ucas has warned that disadvantaged students could be “squeezed out” in the years to come as a rising 18-year-old population is set to increase competition for places on the most selective courses.

The report estimates it could take 332 years to close the equality gap at highly selective institutions unless urgent action is taken to accelerate progression.

The UK’s most selective universities would each only need to admit an extra 70 students from the most disadvantaged backgrounds in England every year to close the equality gap by 2030, Ucas has suggested.

Without intervention, there is potential for widening access progress for undergraduate programmes to stall, and possibly reverse, the report says.

It comes as figures in the first Ucas 2020 End of Cycle report show that record proportions of UK 18- year-olds applied (41.5%) and were accepted (37%) into university or college this year, despite widespread concern that demand for higher education would fall due to the pandemic.

There were also record numbers of acceptances from the lowest participation areas and a record entry rate for students receiving free school meals (FSM).

Higher tariff providers and medicine courses accepted more disadvantaged students, but Ucas said the equality gap “remains stark” as advantaged students are still nearly 25 times more likely than their disadvantaged peers to be placed on medicine courses.

The report calls on universities and colleges to increase the number of higher education places amid the growing 18-year-old population and to ensure disadvantaged students do not miss out.

Ucas forecasts there will be around an additional 90,000 UK 18-year-old applicants by 2025.

Clare Marchant, Ucas’ chief executive, said: “Ensuring disadvantaged students, including those who have experienced significant educational disruption, are supported in accessing HE in 2021 will be critical.

“Looking further ahead, advances in widening access and participation cannot be taken for granted, and there is much work still to be done.

“Ensuring a sustainable increase in higher education and apprenticeship places to ensure availability for the most disadvantaged students will help manage impending pressures on equality.”

Dr Tim Bradshaw, chief executive of the Russell Group – which represents the most selective universities in the UK, said: “We know the number of disadvantaged and under-represented students going to university is rising, but we also know there is more to do.

“Our universities will continue to do their part – earlier this year we saw a significant increase in the number of students from the most underrepresented areas taking up a place at higher-tariff universities reflecting our members’ determination to ensure young people were not unfairly affected by the challenging circumstances around this year’s exams.”

But he added that “tackling educational inequality is not a job for universities alone”.

A Universities UK (UUK) spokesman said: “While it is positive to hear of the progress in closing equality gaps, more can be done, and this will be important with the number of 18-year-olds in the population projected to grow.

“Universities are addressing a number of challenges and disparities faced by the most disadvantaged groups in their applications to university, and UUK will continue to work with its members to remove any barriers students may face while studying.”