Some 72 people have died since the start of the year amid intense rains, overflowing rivers, mudslides and flooding which are the worst seen in Peru in two decades, authorities said.

Prime minister Fernando Zavala has updated the number of dead to 72 in comments to local radio station RPP.

The government says 374 people were killed in 1998 during a similar period of massive rains and flooding.

The problems are affecting more than half the nation, officials said.

Lima has been without a 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.

Earlier, President Pedro Pablo Kuczynski said Peru's coastal region has not seen such environmental calamity since 1998.

Across the country, overflowing rivers have damaged 115,000 homes, collapsed 117 bridges and left people trapped on roofs waiting for rescue.

Mr Kuczynski announced on Friday he was declaring Peru's Central Highway in a state of emergency and boosting funds for reconstruction.

The highly unusual rains are being caused by El Nino, which generates a warming of surface waters in the eastern Pacific Ocean, and are expected to continue for another two weeks.