Six people have been killed following a weekend of storms, floods and a landslide across parts of Europe.

In France and Italy, torrential rain killed four people and left one missing after it caused flooding and a landslide that swept away a motorway viaduct.

Meanwhile, thunderstorms and strong winds in western Greece led to the deaths of two people who were aboard a boat moored next to a pier in Antirio.

Two French departments were still under Meteo France amber weather warnings on Sunday night, while flood sirens sounded once again in waterlogged Venice.

In Greece, the country's meterological service said the extreme conditions would dissipate as the storms moved further east by Monday.

The rain was the latest in a two-week wave of extreme weather in the region.

Part of a viaduct serving Italy's A6 motorway near Savona in the northern region of Liguria running between Turin and France was washed away by what appeared to be a mudslide, leaving a 30-metre (100-foot) gap in the road.

SIAS, the company operating the highway, said it was carrying out investigations to assess the situation.

Officials said there were no signs of any casualties despite a sniffer-dog search of muddy debris.

Pictures of the damage revived memories of the 2018 collapse of the Morandi bridge at Genoa, only 50 kilometres (30 miles) away, which claimed 43 lives.

In the Piedmont region, a 52-year-old woman who was missing after her car was swept away when a river burst its banks was found dead Sunday. Local media reported that two other people in the car had managed to escape in time.

The worst hit region in Italy was Alessandria, south of Turin, where 200 people were evacuated and 600 left stranded. One woman was reported missing, Italian media said.

Another 500 people were evacuated further north in the Aosta Valley, where roads were closed because of the risk of avalanches.

In France, two people died and at least one was missing as high floodwaters swamped cars and turned roads into rivers.

One body was found in the village of Le Muy, just north of France's Mediterranean coast, local officials in the southern Var region said. It was found near where a rescue dinghy carrying three members of the fire brigade and three civilians had capsized on Saturday, with one of the civilians subsequently reported missing.

The second body, of a man in his 50s, was found in the village of Cabasse in a car, the local authorities said, without giving further details.

A third man, in his 70s, was still missing in the village of Saint-Antonin-du-Var after going out during the night amid heavy rain.

The A6 bridge near Savona Italy was swept away by a huge landslip on Sunday REUTERS

The town of Roquebrune-sur-Argens in the Var region was particularly badly affected and only accessible by boat or helicopter, the local authorities said.

Several rivers burst their banks across southeastern France, causing major damage as homes were flooded and trees, cars and boats were swept along by the waters.

Rainfall continued on Sunday, but was less intense.

Some 4,500 households have been left without electricity across Var and Alpes-Maritimes. In some areas of the Var region, the equivalent of two or three months of rain fell in just 24 or 48 hours.

Jean-Luc Videlaine, prefect of Var, told AFP that the rains had been of "historic" intensity, adding that the damage would be "considerable". Although water levels were now going down, he added that the situation was "far from returning to normal".