A JUMP in the number of Aboriginal women in custody has led to a marked increase in the number of women imprisoned in Australia.
A Bureau of Statistics report shows the number of Aboriginal and Torres Strait Islander female prisoners has risen by 20 per cent since June 30 last year, compared with a 3 per cent rise in non-Aboriginal female prisoners.
Prison policy expert Eileen Baldry, of the University of NSW, said the increase should be cause for alarm.
''Over the past 15 years the rate of Aboriginal women in prison has soared,'' she said.
''That raises some interesting questions. Are Aboriginal women innately more criminal than non-Aboriginal women? No, they are not.''
She said Aboriginal women often lacked the social support given to the general population, while being at higher risk of domestic violence, mental or cognitive impairments, homelessness and poverty.
Dr Baldry said the rate of imprisonment had increased despite warnings that improved support mechanisms were preferable to jail.
''It has continued despite warnings that there should be other ways to deal with this, largely through providing support for these women,'' she said.
Figures in the Statistics Bureau's report, titled Prisoners in Australia, show the number of women in prison has grown by 48 per cent over the past decade while the number of male prisoners has risen by 29 per cent.
The bureau's director of the National Centre for Crime and Justice Statistics, Fiona Dowsley, said female prisoners made up only a small proportion of the overall prison population, with 2201 females in custody nationally.
''Females now make up 7 per cent of Australia's total prisoner population,'' she said.
There are 29,383 people behind bars in Australia, an increase of 1 per cent since 2011 and 31 per cent since 2002.
The Northern Territory has the nation's highest imprisonment rate of 826 per 100,000 adults, followed by Western Australia with 267 per 100,000.
Assault was the most common offence for males, accounting for 17 per cent of prisoners, followed by sexual assault, which accounted for 15 per cent.
Drug-related crime was the most common reason women ended up in jail, accounting for 17 per cent of cases, followed by assault, which accounted for 14 per cent.
The prison population is young, with median ages of 33.9 years for men and and 34.6 for women.
Most prisoners had done time previously, with 55 per cent having served a sentence in an adult prison before their current spell inside.
About 80 per cent of prisoners were Australian-born, with Aboriginal and Torres Strait Islander people making up just over a quarter of the prison population.