KANDHKOT: Immense fog and leakage from the gas pipeline caused 11 units of the Guddu Thermal Power Plant to shut down due to tripping, officials said Tuesday.

The tripping of these 11 units caused suspension of electricity for 12 hours in various areas of Sindh, Balochistan and Punjab. Authorities said the units will be restored as soon as the gas leakage is repaired.

The Guddu Thermal Power Plant has 17 power units, out of which only six are currently working.

Pakistan was plunged into darkness after a key power transmission line broke down early on Sunday in an incident being initially blamed on a rebel attack, the latest reminder of the country's crippling energy crisis.

Take a look at: Parts of Pakistan still without electricity, following breakdown

The power failure, one of the worst the country has experienced, caused electricity to be cut in major cities throughout the country, including the capital Islamabad.

The tripping of Guddu power plant's transmission lines affected the 500KV power line from the national grid, forcing Jamshoro and Bin Qasim power stations to shut down.

Pakistan's electricity distribution system is a complex — and delicate — web and a major fault at one section often leads to chain reactions and breakdowns of power generation and transmission.