Figures which show that only a fraction of students at some of Scotland's top universities come from the most disadvantaged backgrounds have been described as shocking by students' leaders.

Three of the country's four ancient universities took in fewer than 100 Scottish students from deprived backgrounds in 2010/11, according to statistics obtained by the National Union of Students (NUS) in Scotland.

St Andrews University recruited just 13 Scots from such backgrounds, or 2.7% of its Scottish intake last year. The universities of Edinburgh and Aberdeen admitted 91 and 51 students, respectively.

Robin Parker, president of NUS Scotland, said the figures should act as a "wake-up call", adding: "These statistics are shocking. For an institution like St Andrews to take 13 students from the poorest backgrounds last year shows just how far we have to go.

"University places should be given to those that have the most talent and potential. Unless institutions do more to widen access, they're missing out on some of those with the most potential, that could get the best degrees, and quite frankly, not doing their job properly."

The figures, obtained following a freedom of information request by the student body, were compiled using the government's Scottish Index of Multiple Deprivation (SIMD).

Students were deemed to be from a poorer background if they were from one of the least affluent 20% of communities. The NUS said Scotland has the worst record on widening access in the whole of the UK and that the figures show how far some institutions have to go.

Aberdeen's 51 students represented 3.1% of its Scottish intake last year, while Edinburgh's 91 amounted to 5% of the intake. Scotland's fourth ancient university, Glasgow, recorded higher figures. It admitted 303 students from the most deprived backgrounds, more than 10% of its intake in 2010/11.

The University of St Andrews said that for every three offers it makes to students from deprived backgrounds in Scotland, only one accepts, despite "significant" levels of scholarship support.

A spokesman said: "The top universities in this country are open and accessible to all - but we need much more support from society at large to engender the belief in young people that the brightest can come here, and succeed."