Tajikistan's authorities drastically rationed electricity supplies to the capital Dushanbe on Friday in response to a severe cold snap that has paralysed the ex-Soviet republic's power grid.

Residents of Dushanbe, which has a population estimated at 500,000 to one million, will receive only 10 hours of electricity a day, although government buildings in the centre are not affected, Sharifkhon Samiyev, the head of state electricity company Barki Tozhik, said on state television.

Outlying regions in the mountainous Central Asian country of 7.2 million people will now receive at most 90 minutes a day of electricity, down from the four-hour limit imposed since October.

"The population of our country faces huge problems in ensuring heating and power due to the abnormal freeze in our country," Samiyev said.

The capital had previously been spared rationing.

Winter temperatures that usually hover around zero degrees Celsius (32 degrees Fahrenheit) have plunged to below freezing, reaching minus 20 degrees Celsius (minus four degrees Fahrenheit) in some areas.

The cold has iced over a river feeding the lake that drives the Nurek hydroelectric power plant, with an impact on supplies right across the country. Wells and other sources of water supply have also been disrupted.