Scotland's top universities have been urged to recruit more students from further education colleges.
The National Union of Students said a change would boost levels of students from less well-off backgrounds.
Ancient universities do not routinely admit FE students with relevant qualifications straight into the second or third year of a degree course.
NUS Scotland said the practice discouraged poorer students from applying for degree courses.
Many college students take qualifications which, the NUS argues, are roughly equivalent to early university education.
President of NUS Scotland Robin Parker said they should be able to complete a degree in less than the standard four years at the ancient universities - St Andrews, Edinburgh, Glasgow and Aberdeen.
He said: "It basically creates a two-tier system where students who have made a decision to go to their local college are forced into going to universities that are less highly regarded.
"They don't have that opportunity to have that second chance of going to one of the prestigious universities we have in Scotland. Fundamentally that's not fair."
University leaders have cautioned that study at degree level is different because it is less structured and more emphasis is placed on self-directed learning.
A spokeswoman for Universities Scotland said the number of fast-tracked college students had nearly doubled to 3,370 over the past three years.
Universities were open to receiving more further education students as a means of widening access to higher education, she added.
The NUS will make the call for the ancient universities to alter their approach, at a conference on Higher Education in Edinburgh on Thursday.