NSW prisons are bursting at the seams with the number of adults behind bars reaching its highest level in 20 years, with Indigenous Australians massively over represented.
The latest Bureau of Crime Statistics and Research statistics show a 13 per cent increase in NSW's jails over the past two years, with 12,995 prisoners recorded as of March this year - and that doesn't include those held in police cells.
The state's Indigenous population continues to have a disproportionate number of prisoners, with 3166 adults behind bars as of March this year, bureau director Don Weatherburn told AAP.
That figure makes up 65.3 per cent of the total number of prisoners in NSW Jails.
The number of Indigenous defendants on remand grew by 11.4 per cent over the last 12 months. The number of sentenced Indigenous prisoners actually fell by 0.10 per cent over the same time period.
Mr Weatherburn said Indigenous people were usually the first to feel the effects of a tougher criminal justice system.
However, as of March, there were 281 juveniles overall behind bars - a 9.4 per cent decrease over the past 12 months.
"Juveniles aren't offending as much as they used to," Mr Weatherburn said.
While the reasons for this drop were unclear, Mr Weatherburn said the end of the heroin epidemic played a part.
Although high, the growth in adult prisoners has slowed, but it was unclear if the numbers would steady off or increase again.
"Do they (police, courts) continue getting tougher?" he said.
"Or, now that we have a large prison population, do we use prison more sparingly?"
Most of the increase has come from prisoners who've been refused bail, according to the figures released on Monday.
The main reasons for the spike have been changes in the bail act, congestion in the district criminal court and increases in arrests, Mr Weatherburn says.
To deal with the increased inmate population, $3.8 billion committed by the government will fund an additional 7000 beds and staff to operate the facilities, a Corrective Services NSW spokeswoman says.
The funds covered two rapid build prisons - one in Wellington, the other at Cessnock - the re-opening of Berrima Correctional Centre and the opening of Illawarra Reintegration Centre and Mary Wade Correctional Centre.