Islamabad: Pakistan's port city of Karachi was hit by a major electricity breakdown Sunday.

Electricity transmission from the national grid to Karachi was abruptly suspended, causing a power shutdown in the city's Nazimabad, Defence, Sharea Faisal, Gulshan-i-Iqbal, Nursery, Shah Faisal, New Karachi, Clifton, Landhi, Korangi and other areas, Dawn reported.

The breakdown was caused by a technical fault in one of the high voltage transmission lines supplying electricity to Karachi from the national grid, an electricity company's spokesperson said.

The 500kv transmission line tripped due to humidity and fog, which carry high water vapour content. The repair work would take hours, the spokesman added.

Sindh province's Governor Ishratul Ibad Khan ordered the officials to ensure resumption of electricity supply to the city at the earliest.