"[We are] currently ranked ninth in the world in terms of prison population, with approximately 160 000 inmates," he said in a speech prepared for delivery.
At least 30% of those detained were awaiting trial.
Ndebele was speaking at a meeting with senior leadership of the Police and Prisons Civil Rights Union and the Public Servants Association of South Africa in Pretoria.
The problem of over-crowding was a priority, he said.
"That our offender population has remained constant, whether you remove pass laws, group areas, or apartheid laws, should make us search more urgently for answers to the high prison population in South Africa," he said.
The correctional services department hosted a colloquium on overcrowding, alternative sentencing, and the White Paper on Remand Detention in South Africa in November last year.
Violence and unrest
?"The recommendations of the colloquium are currently being considered for implementation," the minister said.
In January, three awaiting trial prisoners were killed and 65 others were injured in gang-related violence at the St Albans correctional facility in the Eastern Cape.
The Congress of the People blamed the unrest on overcrowding.
A few days earlier, another riot occurred at the Groenpunt prison in the Free State.
Four warders and around 50 inmates were injured when inmates torched their cells and parts of the prison facility.
The prisoners were reportedly complaining about some of the warders as well as the quality of food they were fed at the prison.
The Inkatha Freedom Party said then the incident reflected the problem of overcrowding in the country's prison facilities. – Sapa