Many Nigerians have once again been left without state-supplied electricity for several hours, three weeks after the president apologised for the last nationwide outage.
Distribution firms first reported problems with the national grid on Friday evening.
They have assured customers that work is under way to restore power.
Local media report that this is the fifth such collapse this year.
Nigeria generates too little electricity to supply its population of 200 million people, generally hovering at around 4,000 megawatts a day, the BBC’s Ishaq Khalid in the capital, Abuja, says.
The country has installed capacity of 12,500 megawatts, but on a good day produces only a fraction of that, Reuters news agency reports.
Last month, Nigeria’s President Muhammadu Buhari said he deeply regretted the inconvenience caused to people across the country by simultaneous fuel shortages and a national power grid collapse.
At the time, he added the government had worked «tirelessly» to fix problems at thermal stations, which had coincided with a «dip in hydroelectric generation due to seasonal pressures».