Four people died when mudslides hit their homes in the border area between Italy and Switzerland overnight on Saturday, and a fifth was missing near the Italian port city of Genoa after days of torrential rains and flooding.

Severe storms over the past few weeks have again exposed the fragile state of infrastructure in many parts of Italy, where poor planning and widespread illegal building increase the threat posed by flooding.

Heavy rains for much of the past month have caused chaos in many areas of Italy, flooding city streets and causing hundreds of millions of euros damage, three years after seven people were killed in severe floods in 2011.

Authorities said a 70-year-old man and a 16-year-old girl died when their house in Cerro di Laveno, near the border with Switzerland collapsed in a landslide late on Saturday night.

Swiss authorities reported two women died when a mudslide hit a building in Davesco-Soragno, on the Swiss side of the border.

A third person, a 44-year-old Italian, was rescued from the building rubble and hospitalised. Checks for further missing persons are continuing, police said.

A 67-year-old man, reported missing in Serra Rocco, a village near Genoa in the northwestern Italian region of Liguria, was still not accounted for yesterday.