Students are paying record levels of rent as accommodation costs have soared by one-fifth in just four years, according to research published yesterday.

St Andrews remains the most expensive university town in Scotland to rent student accommodation and, along with Glasgow and Edinburgh, the average rent is significantly higher than that of the UK as a whole.

The problem is exacerbated by increased demand for private rented accommodation from young professionals unable to obtain mortgages because of the credit crunch who are now renting rather than buying.

And rising rents may now make the option of parents buying flats for their children to live in while they study more cost-effective, providing they are able to secure a second mortgage from lenders in the current climate.

The National Union of Students in Scotland said restricting the number of House in Multiple Occupation (HMO) licences issued by local authorities by means of quota systems - which in effect places limits on the size of the student population in an area - would simply force rents up even more.

An undergraduate can now expect to pay on average £61.64 a week for accommodation, which is almost £10 more than the 2004 figure of £52.44.

However, in St Andrews the average weekly rent of £82 is around a third higher than the UK average. The town is now the fifth most expensive place to rent student accommodation in the UK behind London, Middlesex, Cambridge and Guildford.

Average weekly rents in both Edinburgh and Glasgow are also above the UK average. Edinburgh, where the average is £71.06, is now marginally more expensive than Glasgow, where the figure is £69.34. Edinburgh is the UK's 13th most expensive university town and Glasgow is the 14th.

Rents in Scotland's two largest cities are considerably higher than in the third and fourth biggest cities. Aberdeen, where the average weekly rent is £58.22, is the 41st most expensive university town in the UK and Dundee, where rents are just £54.82, is 54th.

London is the most expensive place to study, with an average weekly rent of £102.65, the research showed, while the best-value towns are Middlesbrough, Stoke, Wolverhampton, Crewe and Bradford where rents are between £40 and £45 a week.

The research, based on more than 44,000 properties in 76 university towns, was conducted by the website accommodationforstudents.com.

Gurjit Singh, president of the NUS Scotland, said: "These statistics simply highlight once again the intense financial pressure students are subject to.

"Our own research tells us that more than a third of students in Scotland have considered dropping out because of financial hardship, and rent is one of the biggest costs faced by students.

"Students represent a large proportion of those who rent private accommodation and rising rents reinforce the case against the policy of subjecting HMOs to quotas, as this will only limit choice for students and have the effect of further pushing up rents."