Bridges were swept away and villages hit by mudslides and floodwater in Italy's Tuscany and Liguria regions on Wednesday during torrential downpours that killed five, officials said.

Previous reports had put the number of dead at nine.

Up to 500 millimetres (20 inches) of rain fell in just a few hours overnight Tuesday to Wednesday, according to weather reports.

Around 10 people were reported missing.

The areas worst hit were the Spezia region and the picturesque Five Lands tourist destination, where three people died. Two bodies were also recovered from a mountainous region in northern Tuscany.

A 50-year-old woman and an elderly couple from the village of Borghetto were swept to their deaths in a river of mud, according to authorities in La Spezia.

Another young woman was swept along for over a kilometre but was later found exhausted and in a state of shock.

The situation was becoming serious, said the leader of Liguria's first aid and rescue service, Renata Briano, "especially since we don't have any news of what is happening in some isolated areas."

The director of Italy's first aid and rescue service, Franco Gabrielli, said: "Right now the priority is getting to people before nightfall."

Authorities were "working to get basic services back on as in some areas there was no electricity, water, gas and communications are difficult," he said.

Among the lucky ones were two tourists who were found safe and sound after having been reported missing from Vernazza, one of the five villages that make up the Five Lands.

"When the water reached my thighs, I was swept up by a rescue worker and carried to safety," said tobacconist Aurora Moggia from Monterosso, who watched as a minute later a landslide of mud and rubbish swept through the town.

Inhabitants in Borgetto Vara and Brugnato were rescued by monks in a nearby monastery who provided shelter to around 30 people, feeding them and giving them dry clothes.

"Italian citizens are having to pay the price for... overbuilding authorised in areas at risk which instead should be freed up by demolishing dangerous buildings," environmental organisation WWF Italia said in a statement.

As further rain hampered rescue work, local authorities asked residents not to go out or to use private cars.

"All this happened in just a few minutes, it's shocking," said a local member of the civil protection agency at the site of a landslide which devastated the town of Aulla, where 300 people took refuge overnight in a gym.

The bad weather was expected to spread to the rest of Italy on Wednesday, and Rome's Mayor Gianni Alemanno placed firemen and rescue services on alert though the capital appeared mid morning to have escaped the worst of the rain.

Five days earlier Rome was paralysed by a violent storm that flooded the city, halting public transport and forcing many Romans to stay indoors.