With a death toll that continues to rise - now standing at 480 - Ecuadorean President Rafael Correa has said rebuilding the country will cost billions of dollars and may inflict a "huge" toll on the economy.

Two days after the magnitude 7.8 quake, traumatised survivors begged Correa for water in the city of Portoviejo, while a soccer stadium in the beach town of Pedernales served as a makeshift relief centre and morgue.

Afraid of staying indoors, or with no home to go back to, families huddled in the streets, while police and soldiers patrolled in an effort to control looting.

Seeing the devastation first hand, a visibly moved and grim-faced Correa warned that Ecuador's biggest disaster in decades would put a big toll on the poor Andean country of 16 million people.

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Relief workers were confronted with swaths of flattened homes, roads and bridges as they surveyed the destruction wrought by Saturday night's quake, and the death toll was expected to rise.

"Reconstruction will cost billions of dollars," said Correa in Portoviejo, where survivors swarmed round him asking for aid. The economic impact "could be huge," he added later.

Michael Henderson, at risk consultancy Maplecroft, told Reuters news agency that Ecuador was less well equipped to recover than Chile, where a 2010 earthquake caused an estimated $30bn in damage.

The quake struck on Saturday night along the northwest coast, while Correa was in Italy. Vice President Jorge Glas - a potential candidate to succeed Correa in the elections next February - flew into the disaster zone within hours to oversee rescue and relief efforts.

Watch: Rescuers scramble to find survivors

But some survivors complained about lack of electricity and supplies, and aid had still not reached some areas. The number of injured rose to more than 2,600.

Shaken Ecuadoreans lined up for food and blankets, slept in the rubble of their destroyed homes or congregated in the street after the most destructive quake since a 1979 magnitude 7.7 quake killed at least 600 people and injured 20,000, according to the US Geological Survey.

Fears of looting spread as in Portoviejo people stole clothes and shoes from wrecked buildings and police tried to control crowds. A former social security building was ransacked for aluminum window frames and cables by people hoping to sell the materials.

"I have to take some advantage from this horrible tragedy. I need money to buy food. There's no water, no light, and my house was destroyed," said Jorge Espinel, 40, who works in the recycling business.

Elsewhere, armed men robbed two trucks carrying water, clothes and other basics to quake-hit beach locality Pedernales.

Numbed by trauma

There, survivors curled up on mattresses or plastic chairs next to flattened homes. Soldiers and police patrolled streets while rescuers searched for any survivors.

Tents sprang up in the town's football stadium, where relief workers treated the injured, distributed water, food and blankets, and stacked coffins.

Numbed by their trauma, bruised and bandaged survivors wandered around, while the more seriously injured were evacuated to hospitals.

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More than 300 aftershocks rattled the stricken region, leaving survivors huddled in the streets, fearful that their already damaged homes would cave in.

"We're scared of being in the house," said Yamil Faran, 47, in Portoviejo. "When ... the aftershocks stop, we're going to see if we can repair it."

Some 130 inmates climbed over the collapsed walls of the town's low-security El Rodeo prison, although more than 35 were recaptured.

The government has mobilised about 13,500 security personnel to the affected areas.

Nearly 400 rescue workers flew in from various Latin American neighbours, along with 83 specialists from Switzerland and Spain. The United States said it would dispatch a team of disaster experts, while Cuba was sending a team of doctors.