Most cities across the country was left with no electricity due to fault in high-tension transmission lines on Monday morning.
The electricity outage hit cities in Sindh, Khyber Pakhtunkhwa, Punjab and the federal capital after transmission lines from Guddu power station developed technical fault.
The Ministry of Energy, in a statement, said the decrease in system frequency of the national grid was reported at 7:34 am, adding that efforts are underway to restore the power supply.
Sources said power plants in Guddu, Jamshoro, Muzaffargarh, Haveli Shah Bahaduur, Baloki, were affected by the power breakdown.
In Lahore, consumers in areas of the Mall Road, Kanal Roald and other areas are facing the disruption in power supply while Orange Line Metro Train service has also been suspended.
The electricity supply to 117 grid stations of Islamabad Electricy Supply Compnay was also disrupted, affecting different areas in the capital city and Rawalpindi.
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In Karachi, the electricity is unavailable in Gulishtan-e-Johar, Pehlawan Goth, Johar More, Bhittaiabad, Nazimabad, Golimar and other areas.
Sources said it could take hours to restore the power supply across the country.
People from different cities thronged to social media to report the electricity failure.
Energ Minister Khurram Dastgir, in a statement, said it was not a major fault, adding that power supply across the country would be restored within 12 hours. He said most of the system was shut down in the night due to low demand of electricity in the winter season and it was switched on in the morning. Mr Dastgir said when the system was restarted, decrease in frequency was reported between Jamshoro and Dadu, causing breakdown in the country.
In October last, a massive breakdown hit the several parts of country when two 500kv lines tripped.