Forest fires burning in at least 15 of Russia's national parks have caused more than 50 deaths, the Ministry of Natural Resources said Saturday, dpa reported.
Moscow was again shrouded in smoke from nearby peat fires. In some places, visibility was reduced to less than 100 metres.
Authorities told the population to stay indoors if possible.
Football matches in the Russian league due to be played at the weekend in the capital were postponed.
Four people were killed in a traffic accident on Friday night after the driver lost control of his vehicle because of the smoke, the Interfax news agency reported citing police sources.
Hundreds of thousands of emergency workers are fighting the fires in several regions across the country.
The official death toll stands at 52. Hundreds have been injured and thousands made homeless.
Russian aid groups said they believe the real toll is much higher.
Poland said it wants to send 160 firefighters to Russia. Moscow has yet to respond to an offer of help from the German government.