Five people have died as forest and brush fires flared up again in Russia's southern farmlands, burning down 532 homes and buildings, officials said on Friday.

"The bodies of five people were found in the fire, but this is preliminary information," Mikhail Murzayev, the head of the investigative committee in the Volgograd region, told the RIA Novosti news agency.

Strong winds stoked fires that destroyed 532 buildings, including 400 homes, in about 20 villages in the Volgograd and Saratov regions, an emergency ministry spokeswoman said on Friday. The Volgograd region lies some 1,000km southeast of Moscow.

"Thousands of people are without shelter," the spokeswoman, Irina Andrianova, was quoted by the agency as saying.

Russian President Dmitry Medvedev on Thursday ordered authorities to mobilise all means to fight the fires as the emergency ministry warned the fires risked spreading to other southern regions.

Prime Minister Vladimir Putin on Friday pledged the two fire-struck regions would receive one billion rubles ($25.4 million) in emergency aid to rebuild after fire storms that have raged for months, the government said in a statement.

A state of emergency was also declared overnight to Friday in the Urals city of Tolyatti to the east as fires devoured some 200 hectares (nearly 500 acres) of forest nearby, Mayor Anatoly Pushkov was cited by RIA Novosti as saying.

Temperatures have fallen in Moscow since an unprecedented heatwave this summer, but in recent days they have still topped 40 degrees Celsius in the southern regions.

Forest fires ravaged about a million hectares in Russia in recent months, destroying whole villages and leaving more than 50 people dead, according to official tallies. Fires also threatened to engulf several nuclear plants.

An emergency alert was lifted on August 23 in the last of the seven regions affected by the fires.