"Yesterday criminal proceedings were started on the suspicion of actions causing a public danger," said a police statement.

The roof of the Lidl supermarket collapsed Tuesday under the weight of heavy snow while the store was still open with staff and customers inside. One woman, reported to be a 22-year-old sales assistant, was taken to hospital with a shoulder injury.

A frantic search for survivors was launched using sniffer dogs and cameras after initial reports said up to six people might have been inside. No victims were eventually found during the three hour search.

The Czech supermarket incident came a day after the roof of an ice rink collapsed under heavy snow in neighbouring Germany, killing at least 14 people.

Lidl said in a statement Wednesday that its supermarkets were built according to "above standard quality and construction methods in accordance with current norms and meeting regular building approval requirements."

"The roof of the Ostrava supermarket was different from the normal architecture which Lidl normally uses," it said. Lidl's spokeswoman in the Czech Republic, Monika Sramkova, said she was unable to give further details of the differences.

"It is a technical thing," she told AFP.

Heavy snowfall in northern Moravia was, apparently, the cause of the accident, the company statement added.

The director of the regional fire rescue service, Zdenek Nytra, told Czech television that they had contacted all the supermarkets in the area because of the danger of heavy snow on their extensive roofs, which often have only a slight slope.

Around 15,000-20,000 people were estimated to be still without electricity in the south-west of the Czech Republic on Wednesday after blizzards cut power lines.

The supermarket will have to be destroyed following the accident, according to the Moravian-Silesian fire service.

Lidl belongs to the German retail chain Schwarz, which also owns the

Kaufland chain of stores, and has conducted a vigorous expansion in the Czech Republic in recent years.

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