Hundreds of wildfires that have swept western Russia and cloaked Moscow in suffocating smog have caused billions of dollars in damage, a newspaper said Tuesday.

The business daily Kommersant said the damage from the fires was expected to amount to about $15 billion _ or about one percent of Russia's gross domestic product. The government has yet to release any damage estimates.

The hottest summer since record-keeping began 130 years ago has cost Russia more than a third of its wheat crop and prompted the government to ban wheat exports for the rest of the year.

Kommersant said a rise in grain prices would likely lead to a spike in inflation and stifle growth.

The acrid smog that has engulfed Moscow for a week eased a bit on Tuesday, but the concentration of pollutants remained high. Prime Minister Vladimir Putin summoned Moscow Mayor Yuri Luzhkov, who said the situation in the capital was difficult but that city health authorities were doing what was needed to help people cope with the heat and smog.

Ambulances calls have risen by nearly a quarter, compared with the period before the heat wave struck, Luzhkov said.

Putin was to tour two villages later Tuesday that were burned to the ground by fires southeast of Moscow to discuss rebuilding efforts. He previously has promised new houses to all those who lost housing in the fires before the fall, and ordered Web cameras placed at burned villages to keep the pressure on local officials to rebuild.

Despite Putin's visits to the areas hit by fires, opinion polls have shown a drop in approval ratings for both him and Russian President Dmitry Medvedev.

Medvedev was slow to interrupt his Black Sea vacation even as fires around Moscow grew worse, and, unlike Putin _ who met with villagers and firefighters _ has mostly conferred with officials after his return.

A nationwide poll of 2,000 conducted by the Public Opinion Foundation earlier this month showed Putin's approval ratings dropping from 63 to 61 percent compared with a survey in late July, while Medvedev saw his popularity drop from 57 to 52 percent. The margin of error for the poll was about plus or minus 3 percentage points.

The business daily Vedomosti quoted Kremlin-linked political analyst Gleb Pavlovsky as saying the Russian leadership was unprepared for the fires.