Friday's strongest aftershock had a 5.9 magnitude and damaged homes in the impoverished region of Huancavelica, which also lies on the coast south of Lima.
Many victims of Wednesday's earthquake were poor, killed when their flimsy mud-brick homes collapsed. Hospitals and morgues were overwhelmed, forcing residents to lay bodies out on city streets.
Teams of volunteers were trying to help emergency crews find the living and treat the injured.
The rescue of a man from the rubble of a collapsed church brought some hope to search teams but others were pessimistic.
"I don't think there are any survivors," said Paul Cana, a 30-year-old miner on a rescue squad.
About 510 people have been confirmed dead and 1,000 wounded since the big quake, the United Nations said on Friday.
Peru's civil defense agency said 453 people died but an official said the toll may rise as the rubble was cleared and information trickled in from more remote areas.
"My feeling is that the number could rise," said Walter Tapia, an operations coordinator for the agency.
The towns of Nazca and Palpa that flank the Nazca Desert -- famous for gigantic images of animals carved into the barren earth thousands of years ago -- were hard to reach.
"We have other populations that were also affected from which we have recently begun to receive reports," Tapia said.
Thousands of people were left homeless by the quake and have been forced to sleep outside.
Pisco, renowned for the grape liquor that bears its name, was hit hard by the quake, along with the towns of Ica and Chincha, where hundreds of prisoners escaped from a jail when the tremor tore the old building apart.
The quake was one of the worst natural disasters to hit the South American country in the last century. In 1970, an earthquake killed an estimated 50,000 people in avalanches of ice and mud that buried the town of Yungay.
