Haze and smoke are spreading through Moscow's streets, even seeping into the Metro network, and some people are wearing face masks indoors.

Reports suggest the city's mortality rate rose by at least 30% in August.

The national death toll attributed directly to wildfires is 52. Nearly 560 fires were still burning across central Russia as of August 6.

Of these, 39 were peat bog fires, 27 of them in the Moscow region alone, accounting for the acrid smoke choking the capital.

Daytime temperatures in Moscow remain close to 40C with little sign of relenting in the next few days.

The smog has been affecting the capital for a week, and appeared to have been easing - before it worsened on August 6.

Air traffic at two of Moscow's international airports has been disrupted.

In the south of Moscow, visibility at the international airport Vnukovo was reduced to 300m, and at Domodedovo airport it was no more than 400m.

Seven regions are under a state of emergency. Nizhny Novgorod, Ryazan and Voronezh are reported to be the worst hit.

Up to 2,000 homes have been destroyed in the blazes, officials say.

Russia has announced it is banning the export of grain from 15 August to 31 December after drought and fires devastated about a fifth of its grain crop.