A cold front has swept across north-western Russia, bringing with it driving rain and high winds in the wake of the devastating heatwave.

The storm hit St Petersburg, the country's second city, as trees came down and buildings were damaged.

Two 50-metre cranes fell on a construction site, seriously injuring the woman driver of one of them.

Across the region nearly 100,000 people had their power cut off.

Forecasters warned that the storm front was heading for the Moscow region. Thunder, torrential rain and even hail are expected.

The Russian capital has been suffering from a return of the poisonous smog aggravated by the fires surrounding the city.

The government has mobilised emergency services to minimise the damage of the oncoming storm.

Meanwhile the authorities have sought to calm fears over the Sarov nuclear centre. They say the main fires in the area have been put out, and have described the level of radiation in the country as 'normal'.

An official website was closed at the weekend after it said the fires had released radioactive material.