Wildfires were raging dangerously close to a shelter housing hundreds of dogs and retired circus animals, animal activists said Thursday, as the death toll from weeks of blazes across Russia rose to 50.

A firefighter attempts to extinguish a forest fire near the village of Dolginino in the Ryazan region, some 180 kilometres southeast of Moscow, on Wednesday. (Associated Press)

Rescuers pulled a body out from a provincial village gutted by wildfires and another person died of their injuries overnight, the Emergencies Ministry said. Almost 600 separate fires were still raging, mostly in western Russia, as the country endured its hottest summer on record.

The director of the animal shelter, in the village of Khoteichi, 64 kilometres east of Moscow, said he and volunteers had already extinguished a fire that came within 150 metres and were bracing for more blazes. The shelter is home to more than 1,800 animals, mainly dogs, but also bears, monkeys, foxes and tortoises.

"With the speed of fire, we don't know if we can save them all," Sergei Serdyuk said of the animals.

Thick smog that had blanketed Moscow partially lifted early Thursday, but could return with no end in sight to a record heat wave, officials warned.

Body found near Nizhny Novgorod

Temperatures of up to 38 C have exacerbated forest and peat bog fires across Russia's central and western regions, destroying close to 2,000 homes.

The forecast for the week ahead shows little change in the capital and surrounding regions, where the average summer temperature is around 23 C.

The body was found in a village near Russia's fifth-largest city, Nizhny Novgorod, about 480 kilometres east of Moscow and the hospital death occurred near Voronezh, southeast of Moscow.

Those regions are among the worst hit.

Prime Minister Vladimir Putin has promised to build new, better homes before winter, and vowed each victim would receive $6,000 US in compensation. The sum is huge in a country whose average monthly wage is around $800 US, and Russian media say some residents may have deliberately torched their dwellings to qualify.

To the east, firefighters focused on beating flames back from a top-secret nuclear research facility in the city of Sarov.

A Sarov news website cited local officials Thursday as saying a wall of fire had been broken down into several smaller blazes. The day before, officials said the closest blaze was still several kilometres from the main facilities at the Russian Federal Nuclear Research Center and as a precaution all hazardous materials had been evacuated.

In the capital, President Dmitry Medvedev fired several high-ranking military officials Wednesday over what he called criminal negligence in fires that ravaged a military base.

Russia has been sent helicopters and planes to help douse the flames from Ukraine, Armenia, Italy, Kazakhstan, Azerbaijan, Emergencies Minister Sergei Shoigu said in televised comments.