Gas supplies to parts of Chechnya's capital Grozny have been cut off after an accident damaged a gas pipeline running through the Russian region.
The gas shortage adds to Chechnya's chronic problems
The accident came shortly before its energy-starved neighbour Georgia agreed a deal with Iran to get extra gas.
Most of Georgia still lacks power and heating after snow and wind knocked down its main power line and explosions ruptured a key Russian gas pipeline.
Russia and its neighbours are suffering from extreme cold this winter.
In Chechnya, the emergency situations ministry and gas utillity experts are searching for the cause of the pipeline rupture, which happened near the city of Gudermes, a ministry official said.
The rupture cut off supplies to the Shali and Kurchaloi districts as well as to the capital.
Chechen rebels have been blamed for previous damage to pipelines, including the explosions which cut off Georgia's gas last Sunday.
The BBC's Natalia Antelava in Tbilisi says Georgians are trying their best to keep warm, but wood and kerosene are all most people have.
Across the country people are queuing in freezing weather to buy alternative supplies like bottled gas, as Georgia suffers its worst energy crisis for years, she reports.
Heavy snow has exacerbated the region's problems, blocking roads, isolating entire villages and preventing emergency delivery of wood and diesel to mountainous areas.
Across the Black Sea, Turkey says it is introducing electricity rationing because of reduced supplies from Russia and Iran.
Iran says it reduced its exports because harsh weather had raised domestic consumption.
The North Caucasus pipeline explosions damaged not only energy supplies but also Georgia's fragile relationship with Russia, our Tbilisi correspondent reports.
Georgia's President Mikhail Saakashvili called the incident a pre-planned act of sabotage by the Kremlin.
Moscow said his statements were outrageous and hysterical and promised to repair the pipeline and supply additional gas via neighbouring Azerbaijan.
But five days on it still has not arrived, our correspondent reports.