Universities responding to a recent consultation on plans for unlimited recruitment of students above the grade threshold said schools were increasingly likely to predict AAB.
Meanwhile, institutions would be happy to make offers of AAB and above to large numbers of students, since they would be a "safe bet" and would not count towards institutions' limits on undergraduate places. As a result, students failing to meet predicted grades might struggle to gain a place, as they may not have a lower offer and, given the pressure on places, could find it impossible to secure one through clearing.
The concerns are summarised in a report published by the Higher Education Funding Council for England about its consultation on teaching funding for 2012-13.
Hefce's paper says universities had raised fears that the AAB policy - and moves to cut any remaining "core" places - could work together to "leave high-grade non-AAB+ students without preferred offers".
It adds that there was "concern that the system will encourage schools to predict AAB+ grades for increasing numbers of students, and that AAB+ offers will be a safe bet for institutions. Those students who ultimately achieved ABB might be at risk of missing out."
The paper also warns that schools might be tempted to enter students for A levels "perceived to be easier" in a bid to help them achieve AAB.
Since the consultation, Hefce has attempted to mitigate the effects of the AAB policy on fair access by allowing elite universities to retain a "core" of below-AAB places to enable them to make more lower-grade offers.