Taskforce Themis was established in July 2018 and led by former NSW Police assistant commissioner Mark Murdoch.

The independent inquiry looked at 322 cases of allegedly inappropriate relationships between Corrective Services NSW staff and prisoners in the decade between 2007 and 2018.

Some 14 cases of physical contact of a sexual nature were substantiated, as as well as nine cases of an intimate letter-writing relationship and 17 cases of non-intimate letter writing, CSNSW said on Friday.

Assistant commissioner Carlo Scassera said the vast majority of staff observed the highest of professional standards.

"While these incidents are rare, it does not mean we don't take the issue seriously and would immediately report to police such incidents that undermine our profession," Mr Scassera said in a statement.

A common factor leading to inappropriate relationships was trauma, either at work or home, which could leave staff vulnerable, he said.

"The best defence is a strong, supportive work culture, which provides training, skills and competencies needed for the job and we have taken immediate action to support our staff and improve practices," Mr Scassera said.

The inquiry found staff of all levels of experience and service could be susceptible.

Corrections Minister Anthony Roberts said staff needed it to be made clear what constitutes an inappropriate relationship and what the consequences may be.

"It is imperative that our corrections staff are mentally strong and resilient and have the confidence to report instances of workplace misconduct, including instances where professional boundaries may have been crossed," Mr Roberts said in a statement.

"The safety of our correctional centres is of fundamental importance to the NSW Government."

This is why the government made sexual or intimate relationships between Corrective Services staff and prisoners an offence, he said.

Australian Associated Press