Families struggle to keep warm

Mr Putin said Mr Gavrin had resigned at the Kremlin's request, and that the controversial governor of the far eastern Maritime region, Yevgeny Nazdratenko, had also tendered his resignation by telephone.

The president called on security chiefs and the Emergency Situations Ministry to investigate who could be prosecuted for the widespread power cuts.

Hospitals in some cities have been taking in a stream of patients with frostbite. Many of them have had to undergo amputations, some without anaesthetic, which is in short supply.

The government has been forced to airlift pipes and plumbers to the Russian Far East for expensive emergency repairs to heating systems.

Coal supplies have also had to be sent urgently to the worst affected regions.

Despite the cold, demonstrators have taken to the streets in some areas to protest against power cuts lasting 20 hours a day, and frost growing on the inside walls of their apartments.

Heart attack

Public television reported last week that a total of 600,000 people were affected by poor heating in the far east, and 18,000 people had no heating at all.

In some regions, temperatures have fallen well below -50 Celsius, causing steel rails on the Trans-Siberian railway to fracture in the cold.

Last month Mr Putin sharply criticised Mr Nazdratenko, blaming him for some of the problems in the region.

Mr Nazdratenko, who has been in conflict with the Kremlin for years, was later admitted to hospital suffering from what aides said was a heart attack.

Temperatures in the regional capital Vladivostok plunged to -27C on Sunday and dropped as low as -36C further north.

Breakdowns in central heating services and electrical generators in the Maritime region left around 10,500 people without any means of warming themselves, local emergency services told Itar-Tass.

On Monday Mr Putin also instructed Kremlin chief of staff Alexander Voloshin to make changes in the management of the country's electricity monopoly, Unified Energy Systems, Interfax reported.

The utility is headed by former Kremlin-insider Anatoly Chubais.