Despite having some of the world's biggest oil and gas reserves, Iran has been facing power shortages as it struggles to supply enough fuel to its power plants, especially in winter when heating demand surges.

"Due to extreme cold, frost, snowfall and the need to cut energy consumption, government offices and schools have been shut in many provinces," Mehr news agency reported.

The closures affect Tehran and more than 20 other provinces, including Alborz, Fars, Hamadan, Isfahan, Kurdistan and Yazd.

On Tuesday night, power outages hit several districts of Tehran, with state television reporting gas supply issues at power plants.

The national electricity company, Tavanir, said it was working to keep plants running but urged a 10-percent cut in gas and electricity consumption.

Iran regularly cites extreme weather and fuel shortages when imposing such shutdowns.

Similar restrictions were enforced on Saturday, a working day in Iran, to curb energy use.

Temperatures plunged to minus 19 degrees Celsius (-2.2 Fahrenheit) overnight in Hamadan, making it the coldest provincial capital, state television reported.

Weather forecasts for Wednesday warn of heavy rain, thunderstorms and strong winds in 13 provinces, with snowfall in mountainous areas, mainly in the north.

In the Zagros mountains, about 300 kilometres (185 miles) west of Tehran, 60 villages remain cut off by snow, with air deliveries underway to provide supplies, Tasnim news agency reported.