Many people are still feared trapped under the rubble as heavy rains have hampered rescue efforts.
At least 1,941 people are known to have died in Haiti in Saturday’s powerful earthquake – a rise of more than 500 on the previous figure, officials say.
Nearly 10,000 people have been injured, and many are still missing after the the 7.2-magnitude tremor.
Rescue work has been hampered by heavy rains brought this week by Tropical Storm Grace to the Caribbean nation.
The UN says about 500,000 children now have limited or no access to shelter, safe water and food.
“Countless Haitian families who have lost everything due to the earthquake are now living literally with their feet in the water due to the flooding,” said Bruno Maes, the UN Children’s Fund (Unicef) representative in the country.
Tens of thousands of people left homeless by the quake had to decide whether to brave the storm under flimsy tarpaulins or risk returning into buildings damaged by the tremor and smaller aftershocks.
The south-west of Haiti appears to have suffered the worst of the damage from the quake, especially around the city of Les Cayes.
“Yesterday [Tuesday] evening, I took shelter near a church, but when I heard the ground shake again, I ran to return here,” city resident Magalie Cadet was quoted as saying by the AFP news agency.
She said so few structures remained standing that people had to relieve themselves on the city streets.
Some hospitals were left overwhelmed and in need of supplies, as medics struggled to treat the injured.
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The earthquake compounds problems facing the impoverished nation, which is already reeling from a political crisis following the assassination of its president last month.
Prime Minister Ariel Henry, who is in power until fresh presidential election can be held, has declared a month-long state of emergency and urged the population to “show solidarity”.
Haiti has been hit by a series of natural disasters over the past years, including Hurricane Matthew in 2016.
The deadliest was the 2010 earthquake which killed more than 200,000 people and caused extensive damage to the country’s infrastructure and economy.