A magnitude 6.2 earthquake struck off the coast of Ecuador on Wednesday, just days after a major quake hit the country killing nearly 500 people.

The latest quake was centred 70 km (44 miles) off the Pacific coast town Esmeraldas at a depth of 10 km, the Pacific Tsunami Warning Center said, not far from the epicenter of Saturday's 7.8 magnitude quake.

Reuters witnesses in the zone said two strong tremors of about 30 seconds each were felt in Cojimies, down the coast in the disaster zone from the weekend earthquake, waking people up and sending them into the street.

It was not felt in the highland capital of Quito.

Ecuador's Geophysical Institute said a 6.2 magnitude earthquake at 3.33 local time (0833 GMT) was followed by a series of after-shocks. There was no tsunami warning.

Saturday's 7.8 magnitude quake killed 480 people, left another 107 missing, and injured more than 4,600.

Hundreds of homes were destroyed and roads torn up in a major blow to the South American OPEC country's already fragile economy.

Supervising rescue work in the disaster zone, President Rafael Correa said the weekend quake inflicted $2 billion to $3 billion of damage to the oil-dependent economy and could knock 2 to 3 percentage points off growth.

Saturday's quake, Ecuador's worst in decades, destroyed or damaged about 1,500 buildings, triggered mudslides. It left some 20,500 people sleeping in shelters, according to the government.

In isolated villages and towns, survivors struggled without water, power or transport, although aid was trickling in.