The separation of powers between Westminster and Holyrood has created serious financial problems for many Scottish students, the Association of Scotland's Colleges (ASC) has said.

Student support is a devolved matter but welfare benefits remain reserved, something the ASC believes is severely hampering many poorer students' attempts to pay their way through further and higher education.

The ASC says the situation is particularly bad for college students, who are more likely to come from poorer backgrounds than their contemporaries at university. The association has written to the Calman Commission to call for the situation to be urgently reviewed.

"Choosing to come to college is a brave move for many of the poorest and most vulnerable people in our society. For many, just being eligible for a student loan will actually have an adverse affect on the amount of welfare they receive, regardless of whether they choose to accept this debt," said Howard McKenzie, ASC acting chief executive.

"Many students also face difficult decisions when it comes to living arrangements with partners, as household income is taken into consideration in the calculation of benefits. A couple who choose to live together may find themselves considerably less well off."

He noted that the average Scottish student working towards a HNC or HND qualification will have to survive on a total household income of under £18,000, which can consist of up to nine different sources of income.

"We are deeply concerned that this level of complexity, alongside the threat of actually being worse off, is a huge deterrent to study for society's poorest people – in other words, those who need education the most. This absolutely has to change," McKenzie argued.

The ASC supports the Scottish Government's proposed move from student loans to a system of bursaries, which the association believes would remove many of the existing hurdles that discourage poorer Scots from continuing their education.