Floods coursed through Italy on Wednesday, damaging agriculture and reviving a controversy over environmental neglect.

Italy's agricultural heartland in the fertile north was particularly heavily hit by the flooding. National agriculture association CIA said mud and water had destroyed orchards and vineyards in the regions of Tuscany, Liguria and Veneto.

Near Milan, heavy rain swelled the Po River by almost 2 metrer in 24 hours, farmers' association Coldiretti said. The civil protection agency warned of dangerous weather from Liguria in the northwest to the southern island of Sicily.

Italy's unstable, mountainous landscape leaves it vulnerable to flooding and landslides, a problem long made worse by the abandonment of farmland and reckless construction.

Coldiretti said 82 percent of Italy's towns had areas at risk of landslides and floods where some 5 million people lived.

"A flawed development programme which has reduced the countryside by 15 percent and eliminated 2.15 million hectares of cultivated land in the last 20 years is far from innocent in this situation," Coldiretti said in a statement.

CIA said this was the latest in a series of setbacks for Italian agriculture, whose profits have already been hit by low prices and a Russian ban on food from the European Union.

Bad weather alone has already cost the sector €1 billion ($1.25 billion) since the start of this year, CIA said.

The civil protection agency issued a "red alert" for most of Liguria, whose main city, Genoa, is still recovering from flooding in early October that buried its streets in mud and debris, killed one man and laid bare planning failures.