QUITO (Reuters) - A shallow earthquake with a magnitude of 6.4 struck Ecuador’s northwest coast on Sunday, in the region of April’s deadly quake, the U.S. Geological Survey (USGS) said.

The quake was centred near the town of Esmeraldas, northwest of the capital Quito, at a depth of about 35 km (22 miles), the USGS said.

The Pacific Tsunami Warning Center did not issue a tsunami warning immediately after the quake.

President Rafael Correa said authorities had not received any reports of casualties or material damage.

“We must remain calm,” Correa said during a telephone call to a state-run television station.

“These are normal replicas, though the fear that people feel is understandable - especially the victims of the April 16 quake.”

The tremor was felt in Quito and the coastal business hub of Guayaquil, with residents streaming out of buildings into the streets, according to witnesses.

Calm quickly returned to both cities after residents saw that no damage had been done.

The coastal region has been hit by a series of quakes since the April 7.8 tremor that killed more than 650 people, the nation’s strongest quake in decades.

In May, two successive quakes measuring 6.7 and 6.8 in magnitude killed one person and caused minor damage.