Peruvian officials say they have run out of tents and urgently need at least 40,000 more to house victims of the devastating earthquake two weeks ago.
Aid agencies said many survivors in the Ica region were living on the streets in unhygienic conditions, and were desperately in need of basic supplies.
French agency Medecins San Frontieres said it was as if the earthquake had struck just a day before.
More than 500 people were killed and 1,300 injured in the earthquake.
The worst damage was in the coastal cities of Ica and Pisco, south of Lima.
Peru's civil defence agency said it desperately needed at least 40,000 further tents, and that its emergency stock of tents had been almost used up during a recent cold snap.
The agency's logistics director, Jose Ernau, said that although 9,000 tents would be arriving in the next few days, "much more than that are needed".
Clearing the rubble will take months
On Tuesday, the UN asked the international community for $37m (£18.3m) for medical help, water, food, tents and blankets.
A spokesman for the French agency Medecins San Frontieres said hospitals in the town of Guadalupe were still overwhelmed and as a result medical care was sub-standard.
Aid agencies said psychological trauma was being left untreated and children have not returned to school.
Last week, aid agencies criticised the government over the slow delivery of aid to outlying areas.
Hundreds of tons of aid have already been donated, but it still does not seem to be getting to where it is most needed, says the BBC's Dan Collyns in Lima.
Meanwhile, the government has embarked on an ambitious reconstruction programme, placing a successful businessman in charge.
He predicts that the first victims could receive new houses in six months' time and has pledged to bypass Peru's notorious bureaucracy.
And as part of the clear-up operation, the National Institute of Culture has been taking stock of the damage to historical sites in the region.
Institute director Cecilia Bakula said the earthquake had taken a "painful toll" on Peru's historical heritage, destroying 32% of the region's 173 monuments and buildings of historical importance.
EARTHQUAKE DISASTER ZONE, AND TECTONIC PLATES
Earthquake struck on Wednesday at 1841 local time
The 8.0-magnitude earthquake was centred just off the coast of Peru
Two tectonic plates clash at this region, the Nazca plate and the South American plate
There is about 7-8cm (3in) movement between the plates a year