Russia's coldest winter in a generation killed seven more people overnight, lifting the death toll in Moscow to 123 and putting huge pressure on the Soviet-era heating and power network.

"The Moscow energy system has never sustained such a load," Anatoly Chubais, chief executive of state electricity monopoly Unified Energy System, said yesterday.

Temperatures in the capital have plunged to a 26-year low of minus 30°C and Mr Chubais was quoted by RIA Novosti news agency as saying that electricity consumption hit a record on Thursday.

Exports of gas and electricity have been cut back to provide for increased domestic demand, and the exceptionally cold weather in Siberia has halted oil production in many places.

Russia is the world's second largest oil exporter and supplies a quarter of Europe's gas.

Temperatures in neighbouring Ukraine dropped to -27°C, and gas giant Gazprom agreed to let Ukraine take extra supplies of Russian gas, thus reducing gas supplies to Europe.

In Minsk, a spokesman for the Belarus weather centre said the overnight temperature of -28.6°C was the lowest ever for January 20, beating the 1907 record of -28°C .

Gazprom, which reduced exports to Europe this week, said its system was working flat out. "Our system is indeed working at capacity in terms of production, transportation and the use of gas from underground storage," a Gazprom official said.

"But it is working stably and we have no doubts that it is going to continue doing so during the period of extreme cold, no matter how long it lasts," he said.

Emergency services in Moscow said that seven people died overnight from exposure, and Interfax reported that a further 22 were being treated in the capital's hospitals.

This would bring to 123 the number of people who have died from cold in Moscow since the end of October, most of them homeless.

A bitter north wind and driving snow kept Moscow shivering yesterday, though the temperature edged above -30°C.

The cold snap has put many trolley-buses out of action, while passenger numbers on the underground railway system have swelled because drivers cannot start their cars. Big display advertising has been banned to save energy.

Meanwhile, at least two people were killed and 15 injured in central Russia yesterday by an explosion in a basement furniture shop that set fire to a five-storey apartment building, an Emergencies Ministry spokesman said.

Russian news agencies said eight of the injured were rushed to hospital and others were treated by medics on the spot.