Maitland City Council made the decision after receiving an independent report last week, which raised concerns including the fire and electrical systems.

The prison, which is managed by council on behalf of the NSW government, will be closed until further notice while an assessment of required repair work and associated costs takes place.

The cost of the repairs and how long they take will remain unknown until the assessment is completed.

The exact nature of the safety issues is yet to be revealed.

MCC general manager Jeff Smith said the decision was not taken lightly.

"But the safety of Council staff, visitors and the Maitland community is of the utmost importance," Mr Smith said.

"As a 170 year old heritage site, Maitland Gaol has always required ongoing specialist maintenance but it has now become clear that the site's safety issues pose a risk to staff and visitors, leaving me no choice but to close the site."

All tours and planned events have been cancelled and refunds will be provided.

Council is working with businesses and community groups who use the historic site and will assist where possible in finding alternate arrangements.

In 2022, the state and federal governments committed $10 million for a major redevelopment of the heritage-listed site, including on-site accommodation, a cafe and upgraded services

It's understood the safety review was conducted in preparation for the redevelopment's final master plan.

Maitland council will provide regular public updates about the status of repair work and ongoing communication with community stakeholders.