Several areas of Karachi faced power outage on Saturday afternoon after a high-tension transmission line of 220 kV tripped, affecting the supply of electricity to the associated grids, according to K-Electric – the utility company responsible for electricity supply in the city.

"Restoration efforts have already begun and are expected to be completed within one hour. Availability of generation supply is enabling restoration to progress swiftly," it tweeted.

Initially, the company had said it had received reports of power breakdown in various areas of the metropolis and was "urgently looking" into them.

In a second update, the power utility said its 220 kV high-tension circuit was affected by tripping in NTDC's NKI-Baldia 1 and 2 circuit supplying to Karachi.

"KE transmission system is intact and restoration is progressing swiftly," it said, adding that supply to all affected grids had been restored and downstream energising was underway.

"Power to all strategic sites has been restored in priority," the KE said.

It later tweeted that power supply had been restored to PECHS, DHA, Nipa, Clifton, Civil Lines, North Nazimabad, Gulistan-i-Jauhar, Gulshan-i-Iqbal, Federal B. Area, North Nazimabad, Bahadurabad, I.I. Chundrigar road, Gulshan-i-Maymar, Jail Chowrangi, Gadap, Orangi Town, Valika, Tower and Memon Goth.

KE said power restoration efforts were still underway in affected areas of North Karachi, Jacob Lines, Shah Faisal Colony, Malir and Baloch Colony.

Meanwhile, the federal Ministry of Energy said that the supply of electricity to Karachi was affected because of tripping in Northern-Karachi Interconnections (NKI) transmission lines Baldia 1 and 2.

"The system in the rest of the country is completely normal. NTDC (National Transmission and Despatch Company) and KE officials are busy restoring electricity supply. The causes of tripping are also being investigated," it added.

Earlier, several residents, including politicians and journalists, shared messages on Twitter reporting outages in their areas.

MQM-P Senator Faisal Subzwari said "half of Karachi" was facing power breakdown and called on the federal government to step up and offer relief.

"There must be reasons but people suffering in this weather consider them excuses. Fed Govt must act to provide relief," he tweeted.

Some people questioned whether others were also facing the problem.

Others mentioned their areas and questioned K-Electric about the reason behind the outage.

The last massive power breakdown took place less than five months ago, plunging the entire country into darkness.

The blackout was reported a little before midnight of January 10 by citizens on social media from across the country, including major urban centres such as Karachi, Islamabad, Lahore and Multan, as well as smaller towns and cities.

Power was restored to most parts of the country by the evening.