At least four people were killed as landslides triggered by torrential rain slammed into buildings on either side of the Swiss-Italian border Sunday, a day after floods in southern France killed five people.

In the rain-drenched southern Ticino region of Switzerland, two people died and one was critically injured when a mudslide slammed into a small residential building.

On the other side of the border, a pensioner and his granddaughter were killed when another landslide engulfed a house on the Italian shores of Lake Maggiore. Three other family members survived.

Those landslides were the latest of many to recently have hit northern Italy and southern Switzerland amid incessant rainfall over recent weeks.

The Italian Liguria region has been doused with as much rain in the first 15 days of November as it normally gets in an entire year.

The tragedies also came a day after storms in southern France left five people dead, when their cars were swept away in flooding.

In one heartbreaking case, rescue workers managed late Friday to drag a father from his car, lodged on a bridge submerged by torrential rains, only to see the vehicle with his wife and two young sons still inside torn away by the raging water.

In Switzerland, the bodies of two local women, aged 34 and 38, were pulled Sunday from the rubble of the three-story apartment building in Davesco-Soragno, near Lugano, after being hit by the mudslide shortly before 2:30 am (0130 GMT), police said.

A 44-year-old Italian man, who was living with one of the women, had been dug out and taken to hospital in a critical condition, police told reporters.

Four others in the building at the time it collapsed had escaped with only minor injuries, while the final resident had not been home.

A wall above the building had crumbled under the rain and set off the landslide, police said.

That tragedy came 10 days after a young mother and her three-year-old daughter were killed when a landslide swept away their house in the same region.

After weeks of heavy rain, southern Ticino has been hit by severe flooding, which worsened when Lake Lugano burst its banks in several places and Lake Maggiore threatened to do the same.

- Digging with bare hands -

Just across Lake Maggiore, a 70-year-old man died Sunday after his house was partially buried in a "sea of mud" unleashed after the rain-doused hill behind the building gave way.

Rescue workers managed to drag his 16-year-old granddaughter from the rubble after more than four hours of digging but she died later in hospital.

Her parents and grandmother survived. The family's small, two-storey villa was the only property affected in Cerro, a hamlet on the outskirts of Laveno Mombello, a popular holiday spot.

A neighbour described how he had been awoken during the night by a huge bang "like fireworks", and seeing rescue workers and the girl's parents "digging with spades, even with their bare hands".

"It was a horrific scene," the neighbour told Italian television.

The tragedy means a total of 11 people have died in Italy in accidents related to the freak weather conditions in just over a month.

That toll was expected to rise to 12 later Sunday as rescue workers continued to search for a man whose car was swept off the road by a torrent of water near the Italian Riviera's main city, Genoa.

Italian Prime Minister Matteo Renzi, speaking from the G20 summit in Australia, said the havoc wreaked by the heavy rain was the result of years of neglect of infrastructure.

"We have had 20 years of land management that needs to be scrapped," he said.

An estimated 70 coffins meanwhile were washed away after 50 metres of retaining wall in a cemetery in the Bolzaneto district of Genoa collapsed. Local residents reported skulls and other bones washing up on the banks of the Polcevera river.