"Many flights are needed... to deliver enough food and water," the President said.

According to Laura Velazquez, the head of Mexico's civil defence authority, the states of Veracruz, Hidalgo and Puebla were hardest hit by flooding brought on by days of heavy rains.

In Hidalgo alone, 43 people were reported missing.

She updated the death toll that had stood at 47 just 12 hours earlier, indicative of the fast-unfolding scale of the disaster.

Mexico has been hit by particularly heavy rains this year, including a record for the capital Mexico City.

In the municipality of Tenango de Doria in Hidalgo state, AFP witnessed residents walking kilometres in search of food and water, with flooded roads inaccessible for most vehicles.

Some carried bundles of belongings with them in the hopes of finding a shelter for displaced people.

A small-scale merchant from nearby San Clemente told AFP he had been stranded with a tonne of vegetables since Thursday. Unable to make it to the market, his precious merchandise will likely go to waste.

Heavy rains often occur during Mexico's wet season from May to October, but last week's downpours were made more dangerous by the combination of a tropical system from the Gulf of Mexico and a cold front from the north, according to meteorologists.

Dwellers of coastal cities and towns in the state of Veracruz, criss-crossed by many rivers, were instructed last Friday to evacuate because of rising waters.

In several high-lying inhabited areas, however, the persistent rains washed away mountainsides that spilled downhill as landslides.

Sheinbaum on Monday batted away questions about possible failures in early warning and preparedness.

"It would have been difficult to have information in advance about this situation, unlike what happens with hurricanes," she said, citing a combination of unpredictable meteorological factors.

Skies cleared in many parts on Sunday, allowing work with heavy clearance machinery to get under way.

64 dead, 65 missing as floods devastate central and eastern Mexico