Chile has deployed thousands of troops and police to restore order in the city of Concepcion after looters ransacked several shops for food.
The growing anger over inadequate relief follows the 8.8-magnitude earthquakethat rocked central Chile on Saturday.
The authorities said on Monday police had arrested at least 160 people for violating a curfew imposed to prevent looting.
Meanwhile, the Chilean government appealed to the United Nations for international aid to help its recovery efforts.
Emergency officials raised the death toll of those killed in the quake to 723 on Monday, and said at least 19 other people were listed as missing.
'Emergency without parallel'
The government faces the stiff challenge of providing aid to thousands of people left homeless across the country.
Michelle Bachelet, the country's president, has promised deliveries of food, water and shelter for thousands living on the streets.
"We are confronting an emergency without parallel in Chile's history," she said, adding that a "growing number" of people were recorded as missing.
|The number of the dead from the quake is likely to increase in the coming weeks [AFP]
Lucia Newman, Al Jazeera's correspondent in Concepcion, said there is "a feeling of desolation" in the city.
"There's no water, no food, no fuel, no electricity. There's been wide looting ... we saw people looting a flour mill.
"At night, the neighbours have been arming themselves with bats, in some cases even with guns.
"People are afraid that groups of gangs will try to go into their apartments," she said.
The United Nations has said it will rush aid deliveries to Chile in response to the request from the government.
"We are prepared to provide assistance,'' Elisabeth Byrs, a UN humanitarian spokeswoman, told the AP news agency.
"It could be quite fast, given that our experts are on standby and were alerted in the region."
Bachelet has said she expects the death toll to rise as the scale of the devastation became clear from coastal towns and villages engulfed by giant waves.
Some coastal towns were almost obliterated, after being first shaken by the quake and then slammed by sea waves.
Angry survivors have taken out their frustration on firefighters delivering water in Concepcion, damaging their vehicles.
"We don't have water or anything. No one has appeared with help and we need more police to keep order," a 78-year-old woman in the badly hit city of Talca, told the Reuters news agency.
Al Jazeera is not responsible for the content of external websites
"There are many people here who are robbing," she said.
Jacqueline van Rysselberghe, the mayor of Concepcion, said the situation was getting "out of control" due to shortages of basic supplies.
But she warned that the looting was "totally unjustifiable".
"We've got a very complicated situation and the people feel very vulnerable," she told local radio.
Saturday's quake also triggered a tsunami that killed at least four people on Chile's Juan Fernandez islands and caused serious damage to the port town of Talcahuano.
More than 60 aftershocks of magnitude 5 or greater were reported in the hours after the quake.
The US Geological Survey (USGS) said the earthquake struck 92km northeast of Concepcion at a depth of 63km at 3:34am local time (06:43 GMT) last Saturday.
Aid organisations and government officials in Britain and the US have offered to help Chileans in their efforts to rebuild their country.