Corrective Services Industries group director Steve Thorpe said nearly 8000 hygienic products were bought by prison inmates in September alone this year - 2000 more than the same time last year.

"There is only one reason to explain such a sharp increase, and that has to be linked to all the NSW Government messaging about the importance of good hygiene," Mr Thorpe said.

"The 'buy-ups' prison grocery scheme encourages inmates to take personal responsibility by teaching them to budget, an important life skill that will assist them when they're released."

Corrective Services NSW provides offenders with basic hand-soap and sanitiser, but they can also purchase additional items on a 'buy-ups' list using their wages or money deposited in their account by families and friends.

Inmates have spent around $31 million on food and non-grocery buy-ups this year.

Assistant Commissioner Corrections Industry and Capacity, Leon Taylor, said revenue from the buy-ups covered the costs of the scheme.

"The system also provides prison employment opportunities with 220 inmates packing and processing buy-ups while learning skills in logistics and warehousing," Mr Taylor said.

Inmates were this year permitted to spend a maximum of $150 per week on buy-ups - temporarily up from $100 - to assist with any extra purchases during lockdown. They can also spend $100 per month on non-food items, such as toiletries.

The top grocery purchases at NSW correctional centres from January-November 2020:

The top non-grocery purchases at NSW correctional centres from January-November 2020: