The intense rains, overflowing rivers, mudslides and flooding being experienced in Peru are the worst seen in in two decades, authorities said Saturday, as the death toll hit at least 72.

Peruvian Prime Minister Fernando Zavala updated the fatality numbers on Saturday morning in comments made to local radio station RPP.

The government says 374 people were killed in 1998 during a similar period of massive rains and flooding blamed on the El Nino climate pattern.

The recent rains have overwhelmed the drainage system in the cities along Peru's Pacific coast and the health ministry has started fumigating around the pools of water that have formed in the streets to kill mosquitoes that carry disease.

A massive landslide and heavy rains left a deluge of water and mud in the streets of Huachipa. (Guadalupe Pardo/Reuters )

Lima has been without water service since the beginning of the week. The government has deployed the armed forces to help police control public order in the 811 cities that have declared an emergency.

"The prices for lemons have gone up, as well as for potatoes and cooking oil," said Sara Arevalo, a mother of five who was shopping at a market in northern Lima. The government has acknowledged that prices have shot up because of the flooding.

North coast hardest hit

The highly unusual rains follow a series of storms that have struck especially hard along Peru's northern coast, with voracious waters inundating hospitals and cemeteries, and leaving some small villages entirely isolated.

Apocalyptic scenes recorded on cellphones and shared on social media have broadened the sense of chaos.

In one video earlier this week, a woman caked in mud pulled herself from under a debris-filled river after a mudslide rushed through a valley where she was tending to crops.

Bridges have collapsed as rivers have breached their banks, and cows and pigs have turned up on beaches after being carried away by rivers.

Evangelina Chamorro Diaz emerges from the mud, crawls over debris 0:48

The storms are being caused by a warming of the surface waters in the Pacific Ocean and are expected to continue for another two weeks.

Even Peru's capital city of Lima, where a desert climate seldom leads to rain, police on Friday had to help hundreds of residents in an outskirt neighbourhood cross a flooded road by sending them one-by-one along a rope through choppy waters.

The muddy current channeled down the street after a major river overflowed. Some residents left their homes with just a single plastic bag carrying their belongings.

People cross a flooded street in the Huachipa district of Lima. (Guadalupe Pardo/Reuters )

The vast majority of people affected by the extreme weather are poor, including many who built makeshift homes on floodplains that had been dry for 20 years, said Jorge Chavez, a general tasked with co-ordinating the government's response.

Chavez said Peru must rethink its infrastructure to prepare for the potential "tropicalization" of the northern desert coast, which some climate models have forecast as temperatures rise.

"We need more and better bridges, we need highways and cities with drainage systems," said Chavez. "We can't count on nature being predictable."