It follows the PBNI being informed of an increase in the risk of attack they face from dissident republicans, with employees living and working in republican areas especially at risk.
“This rally saw those from politics, unions, social workers and others stand shoulder to shoulder with the PBNI workers to utterly condemn these threats,” former Justice Minister Mr Ford said.
“The work of PBNI staff goes right across our community, helping people with housing, employment and education among other matters. They play a fundamental role in the transformation of prisoners and their reintegration into society.
“We once again call for these disgraceful threats to be lifted immediately, allowing probation staff to work in a safe and secure environment.”