At least 40 people have died in fires in the past week, and seven regions are under a state of emergency.

Some fires are in danger of getting out of control, the government said.

Earlier, the defence ministry denied Russian media reports that scores of planes and helicopters had been destroyed.

About a fifth of Russia's grain crop has been destroyed and there was another big rise in the price of wheat on international markets on Monday.

Thousands of people have lost their homes in 14 regions of Russia, the worst-hit being Nizhny Novgorod, Voronezh and Ryazan.

At a meeting with President Dmitry Medvedev, Emergencies Minister Sergei Shoigu said firefighters had managed to protect 360 populated areas in danger of forest blazes. But he warned that the situation was dangerously unpredictable.

About 155,000 people, including 124,000 emergency workers, and more than 20,000 units of machinery are currently being used to fight the fires across Russia, the minister said.

Most of 323 new fires which flared up on Monday were put out. However, 529 fires continued to burn on Tuesday over an area of 172,300 ha (425,762 acres), compared with 460 on Monday.