Three people are dead and 19 others are missing after heavy rains struck Chile over the weekend during the country's usually dry summer months, causing mudslides and water outages in the South American nation.

The rains, which caused rivers to overflow their banks in mountain valleys near Chile's capital, Santiago, have isolated 373 people, the Onemi emergency service said late on Sunday.

The drinking-water supply for over a million households in Santiago has been affected, and Aguas Andinas, the company that provides water to the capital, said rains were making repairs difficult.