The Sudanese internal security and intelligence apparatus evolved into a feared and hated institution after Nimeiri came to power in 1969. During the period of Revolutionary Command Council rule (1969-71), the military intelligence organization was expanded to investigate domestic opposition groups. After the council was abolished, the organization's responsibilities focused on evaluating and countering threats to the regime from the military. It also provided a 400-man Presidential Guard.

The Office of State Security was established by decree in 1971 within the Ministry of Interior. The new agency was charged with evaluating information gathered by the police and military intelligence it was also responsible for prison administration and passport control. The sensitive central security file and certain other intelligence functions were, however, maintained under the president's control. In 1978 the presidential and Ministry of Interior groups were merged to form the State Security Organisation (SSO). Under the direction of Minister of State Security Umar Muhammad at Tayyib, a retired army major general and close confidant of the president, the SSO became a prominent feature of the Nimeiri regime, employing about 45,000 persons and rivaling the armed forces in size. This apparatus was dismantled in 1985.

According to the United States Department of State's Country Reports on Human Rights Practices for 1990, government surveillance, which was previously rare, became intense after the 1989 coup. Efforts were made to prevent contact between Sudanese and foreigners. Civilians, especially suspected dissidents, were harassed, church services were monitored, and activities of journalists were closely supervised. Neighborhood "popular committees" used their control over the rationing system to monitor households.

The Bashir government created a new security body. Generally referred to as "Islamic Security" or "Security of the Revolution," it was under the direct control of a member of the RCC-NS. Its purpose was to protect the Bashir regime against internal plots and to act as a watchdog over other security forces and the military. It quickly became notorious for indiscriminate arrests of suspected opponents of the regime and for torturing them in its own safe houses before turning them over to prison authorities for further detention. A similar organization, Youth for Reconstruction, mobilized younger Islamic activists.

Data as of June 1991