"A failure on the Rabak-Masqar-Sennar-Maranjan-Alhasahisa power line caused the national energy grid to go down," the ministry said in a statement.
The authority did not give any reason for the failure, saying technicians were working to restore power supply.
The outage comes amid months of anti-government protests that began last December as a public outcry against rising living costs and general economic hardships. Mass rallies prompted President Omar Bashir to dissolve the cabinet and declare the state of national emergency.