A magnitude 6.2 earthquake has shaken Ecuador's already devastated Pacific coast, terrifying residents and hindering rescuers searching for survivors of an even bigger quake at the weekend which killed more than 500 people.
The latest big tremor before dawn on Wednesday, which followed several hundred aftershocks from Saturday's 7.8 quake, hit 25km off the island of Muisne on the northwest coast at a depth of 15km, the US Geological Survey said.
That was near the epicentre of Saturday's major quake, which levelled a long swath of the coastline and dealt a major blow to the oil-producing nation's already fragile economy.
Two strong tremors of about 30 seconds each woke people up and sent them running into the street.
No tsunami warning was issued and there were no immediate reports of deaths or major new damage.
Ecuador's Geophysical Institute said there were 17 aftershocks.
Local media said rescue operations were temporarily suspended as hopes dwindled of finding anyone alive from Saturday's quake, which killed 525 people, according to a central government tally.
More than 100 people are still missing and more than 4600 were injured in that disaster, which destroyed about 1500 buildings, triggered mudslides and tore up roads.
Some 23,500 people are sleeping in shelters, their homes and livelihoods crushed.
President Rafael Correa, supervising work in the disaster zone, said the weekend quake had inflicted US$2 billion to US$3 billion of damage and could knock two to three percentage points off growth, meaning the economy could shrink this year.
Lower crude oil revenue had already left the poor Andean nation of 16 million people facing near-zero growth and lower investment, forcing it to seek international financing.
Meanwhile, survivors in isolated communities struggled without water, power or transport, although aid was trickling in.
Along Ecuador's Pacific coast, sports stadiums served as both morgues and aid distribution centres.
Scores of foreign aid workers and experts arrived to help, and about 14,000 security force members were keeping order, although only sporadic looting has been reported.
Rescuers were losing hope of finding anyone alive even as relatives of the missing begged them to keep looking.
"There is still a small margin of time to find survivors," Correa said. "But I don't want to give excessive hope."