Requiring universities' admissions policies to be part of a statutory agreement with the Office for Fair Access would be "difficult and perhaps even illegal", the organisation's head has warned.
John Denham, the Universities Secretary, has said he wants all universities to publish their admissions policies in an effort to make the admissions process more transparent.
With his agreement, he said, David Eastwood, chief executive of the Higher Education Funding Council for England, and Sir Martin Harris, director of Offa, had suggested "that the time is right to bring together higher education institutions' widening-participation and fair-access policies, including transparent admissions systems, into a single document".
Now Sir Martin has warned against interference in admissions amid rumours that universities' procedures could be "vetted".
At an evidence session held by the Innovation, Universities, Science and Skills Committee, Roberta Blackman-Woods, Labour MP for Durham, said universities had "picked up rumours around some sort of interference" in their admissions policies.
"I just wanted absolute clarification that there is not going to be a vetting scheme of admissions policies," she said.
Sir Martin replied: "What Offa can do and what should be done are not necessarily the same thing ... The Secretary of State said recently that he believes each university should have a published admissions policy, and I have actually no problem with that ... My own view, and time will tell whether this is what emerges, is that there is no threat to the sector in any way if they decide that they will each, one by one, publish a transparent admissions policy.
"If you go then to require it to be part of some statutory document, that immediately becomes very much more problematical and not something that I would wish to be associated with ... If you say it should be part of an annual agreement with the director of Offa, then I think that would be difficult and perhaps even illegal."
A spokesperson for Offa said Sir Martin did "not think it appropriate" for admissions criteria to be part of universities' formal access agreement with Offa, and that legislation puts admissions criteria outside of his remit.
Sir Martin told Times Higher Education: "The Secretary of State has asked David Eastwood and myself to look at how higher education institutions' widening-participation and fair-access policies might be brought together in a single document. We are happy to do this.
"He has also asked us to look at how admissions policies might be made transparent, perhaps by being published as an annexe to this new single document or perhaps in some other way. We will give our views by September on how this might best be done. However we take this forward, individual decisions on admissions will remain a matter for institutions themselves."