Oxford and Cambridge have been urged to overhaul their centuries-old college admissions system in a bid to promote diversity and inclusion.

A new report published by the Higher Education Policy Institute (Hepi) think tank recommends scrapping it because it disadvantages those from poor backgrounds.

The procedure, which is unique to Oxbridge, involves pupils applying to individual colleges rather than centrally to the universities, as is normal elsewhere in the sector.

It allows for college tutors to connect with pupils during the interview process and select those they think would be particularly suitable for their mentorship.

It is thought both universities have used this system - or a version of it - since they were founded.

However, Hepi's report says this creates 'significant barriers' for disadvantaged applicants because it is 'difficult to understand'.

It said many pupils do not have access to detailed guidance about 'how to navigate the system'.

And it pointed out there are disparities in outreach spending and grade requirements between colleges, meaning pupils may have different chances of success depending on where they apply.

To address this, it calls for a 'fully centralised system in which applications are assessed by departments rather than colleges' – as is the case at other universities.

Last night, Professor Anthony Glees, a security expert at Buckingham University and an Oxford alumnus, said: 'It is certainly true that there is a problem for the very brightest candidates who come from schools with no experience of what Oxbridge colleges are going to demand and do not offer any real preparation for a rigorous interview with an Oxbridge academic.

'However, colleges are the beating heart of Oxbridge and to break the link between tutors and candidates would be madness. It would destroy the uniqueness of the Oxbridge experience.

'It's a tremendous support system and students love it when it works.'

Chris McGovern, of the Campaign for Real Education, added: 'This proposal will enforce a dead hand of conformity on to the Oxbridge admissions system.

'We need a "horses for courses" approach to admissions, not 'one size fits all'.

'Provision of "diversity" is the whole point of the college system. The college system can be much more sensitive to the needs of a range of applicants from different backgrounds and aptitudes.'

The report said Freedom of Information request data shows the highest-spending colleges allocate 12 times more to diversity, equity and inclusion (DEI) than the lowest-budgeting colleges.

It said these differences contribute to an 'uneven national landscape' and 'risk disadvantaging some students with the greatest potential, particularly those from underrepresented backgrounds'.

It added the system was 'complex and opaque', especially for pupils in 'schools with limited capacity'.

Charlotte Armstrong, author of the report and Hepi's policy manager, said: 'Centralising admissions and outreach would help ensure that all strong candidates are considered fairly, while maintaining the benefits of the collegiate system once students arrive.'

A Cambridge spokesman said it was 'proud of the progress made over the last decade in widening participation, which is amongst the best in the sector.'

They added: 'We are fully committed to attracting and admitting students with the greatest potential to thrive here.'

An Oxford spokesman said: 'We dispute the views of the Hepi report... Oxford attracts students with the greatest academic potential from all backgrounds. 

'The college-based admissions process allows us to draw on a wide range of academic expertise in order to arrive at an informed appraisal of our applicants, recognising the variety of their strengths and aptitudes. The result is a student body with exceptional academic potential, reflecting the diversity of talent.

'Our colleges undertake a great deal of additional outreach activity, enabling deeper and more sustained engagement with schools and communities across the UK.'