Ex-prison guard accused of NSW sex assault

A woman is accused of sexually assaulting an inmate at a juvenile justice centre in Sydney's southwest when she worked there as a guard 20 years ago.

Detectives arrested the 43-year-old former juvenile justice officer at a Padstow Heights home on Tuesday morning.

The assaults happened at the Reiby Juvenile Justice Centre in Airds between 1996 and 1997, NSW Police say.

The allegations were first raised at the Royal Commission into Institutional Responses to Child Sex Abuse.

The woman was refused bail to appear at Campbelltown Local Court later on Tuesday where she'll face three counts of aggravated sexual assault.