Another powerful earthquake strikes off Ecuador's coast, with a preliminary magnitude of 6.2

A second earthquake has hit Ecuador with a magnitude of 6.2, just days after almost 500 people were killed in a powerful quake, the Pacific Tsunami Warning Center says.

The quake was centred 70km west-southwest of Esmeraldas at a shallow depth of 10km, not far from the epicentre of Saturday's 7.8 magnitude quake.

Reuters witnesses in the zone said two strong tremors of about 30 seconds each were felt, waking people up and sending them racing them into the street.

It was not felt in the highland capital of Quito.

There was no immediate word from authorities on the impact of today's quake.

This is a breaking news story. More information will be added as it comes to hand.