(Refiles to change day of week to Wednesday from Thursday)
* Russia says forests contaminated by Chernobyl have burned
* Forestry official says "most" of such fires are doused
* Radiation levels normal in Moscow
* Wind disperses toxic smoke in the Russian capital
(Recasts with Chernobyl, adds quotes, changes headline)
By Alexei Anishchuk
MOSCOW, Aug 11 (Reuters) - Fires have scorched forests contaminated with radiation from the Chernobyl nuclear disaster, a Russian forestry official said on Wednesday, but it was unclear what danger the smoke from such wildfires could pose.
Kremlin leaders are already grappling with Russia's deadliest wildfires since 1972 and a drought that has destroyed crops after what weather monitoring officials say was the country's hottest summer in a millennium.
Fears of stirring up nuclear pollution from the Chernobyl disaster could take the crisis to a new level, though officials said radiation levels were normal in Moscow and it was unclear if smoke from fires in contaminated forests could be dangerous.
"Yes, there have been fires," Vasily Tuzov, deputy director of Russia's forest protection agency, told Reuters by telephone when asked if there had been fires in forests polluted by the Chernobyl accident, the world's worst civil nuclear disaster.
"Most of them have been extinguished now," Tuzov said.
He refused to give more details about the fires, referring to a statement on the agency's website which said that fires covering an area of 39 square kilometres (15 square miles) had been registered in regions with forests polluted with radiation.
The regions affected included Bryansk province, which borders Ukraine southwest of Moscow and was polluted by radioactive dust that billowed across Ukraine, Russia, Belarus and Europe after a series of explosions at Chernobyl's reactor No. 4 on April 26, 1986.
Russian Emergencies Minister Sergei Shoigu said on Aug. 5 that in the event of a fire in forests in the Bryansk region, radioactive particles could be propelled into the air. [ID:nLDE6741EQ]
Greenpeace Russia said in a statement that 3 fires had been registered in badly contaminated forests in the Bryansk region, which was polluted with the nuclear isotope caesium 137.
Radiation levels in the Moscow region were unchanged and within normal limits on Thursday, said on Yelena Popova, the head of Moscow's radiation monitoring centre.
Asked whether fires in the areas contaminated by Chernobyl could bring radioactive particles in the Moscow region, she said the risk was still "theoretical".
"There is a possibility that winds could bring contaminated air from Kaluga or Tula regions if major fires erupt there," she said, referring to two Russian provinces a little under 200 km (125 miles) southwest of Moscow that were also polluted by Chernobyl.
"But our monitoring stations have not registered any increase in such activity so far," she said. <^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ For more stories, analyses, market data, interviews and local detail please click on the following links: The human cost of the heatwave: [nLDE67511Z] Wheat prices and the harvest: [nLDE6721M9] What does it mean for PM Putin: [nLDE67913N] How are Russians dealing with fires: [nLDE67916X] The impact on Russia's economy: [nLDE67902C] World wheat stocks: link.reuters.com/duc73n Russian wheat output: link.reuters.com/web73n Wheat prices: link.reuters.com/kak53n
MOSCOW SMOKE CLEARS
Strong winds cleared the toxic smoke from raging wildfires that has choked Moscow for three weeks on Wednesday, but weather forecasters warned that the smoke could return in 24 hours.
The heat and smoke in Moscow -- which sent pollution levels to the highest levels in decades -- almost doubled mortality rates in the capital and disrupted flights, consumer activity and even trading in Russian stocks and bonds.
Muscovites were greeted with a glimpse of clear skies on Wednesday after a thunderstorm accompanied by strong winds in the early hours dispersed the smoke.
The Emergencies Ministry said the area of burning forests in Russia was almost halved in the past 24 hours to 927 square km (358 square miles) from 1,740 square km (676 square miles), and that nearly 166,000 people were fighting more than 600 fires.
"The forest fires have not ceased," Roman Vilfand, the director of the state weather forecasting centre, was quoted as saying by Interfax news agency.
"As soon as there is windless weather again, the smoke will return," he said. "It has got easier in Moscow but not where the fires are burning."
Pollution levels in Moscow on Wednesday were at safe levels, but the state weather forecaster said in a statement that the smoke could return by Thursday.
Some young Russians rejoiced in the rains in the early hours, dancing in the downpour and cheering as thunder and lightning replaced the grey smoke. (Writing by Alexei Anishchuk and Guy Faulconbridge; Editing by Myra MacDonald)