A UK study by the Sutton Trust found pupils from the independent sector may get more help with the personal statements that accompany application forms as well as having more experiences to write about.
Students applying to a UK university now complete a personal statement giving details of their work experience, extra-curricular activities and other information they believe is relevant to their application.
Ucas, the organisation that administers university applications, believes the statement is a way for a potential student to "stand out from the crowd" – particularly at a time when exam pass rates are at an all-time high. However, Dr Steven Jones, an academic from Manchester University, who looked at the personal statements of just over 300 would-be students, believes they are increasing disadvantage.
His findings suggest private school pupils list more work-related experiences, and these could include stints in places such as banks, law firms or leading businesses. State school pupils listed slightly fewer work placements and these were more likely to include Saturday jobs and visits to businesses arranged by the school.
The report also said writing errors were three times more common in personal statements written by applicants at sixth form colleges than those from independent schools.
"This research challenges the assumption that a personal statement levels the playing field, finding that independent school applicants are more likely to submit statements that are carefully crafted, written in an academically appropriate way and filled with high status, relevant activities," Mr Jones's report found.
"By contrast, state school applicants appear to receive less help composing their statement, often struggling to draw on suitable work and life experience."
Chairman of the Sutton Trust, Sir Peter Lampl, said: "This research suggests the personal statement further disadvantages those from low and middle income backgrounds.
"Good state schools and colleges already help their most able students apply for places in leading universities. This should become the norm."
Robin Parker, president of NUS Scotland, said the report highlighted the "huge barriers" facing students from deprived backgrounds. "We welcome the report's recommendations that universities take into account students' backgrounds when examining their personal statements," he said. "There clearly is more universities can do to ensure students with the potential to succeed aren't being overlooked."
However, John Edward, director of the Scottish Council of Independent Schools, highlighted the small sample involved in the study. "The immense amount of time and work that students put into the admissions process, with the support of their teachers and families, simply reflects their commitment and the fact competition is extremely high for places," he added.
There clearly is more universities can do to ensure students with the potential to succeed aren't being overlooked