BOGOTA (AFP) - A 6.5-magnitude earthquake rattled north-western Colombia Tuesday but there were no immediate reports of casualties or damage, the authorities said.

The Seismological Network of Colombia said the quake struck at 10.43am in the Pacific Ocean, 99km from the town of Nuqui in the department of Antioquia.

The Colombian authorities ruled out the threat of a tsunami.

The Colombian report said it was felt especially strongly in the city of Quibdo, the capital of the department of Choco, where people ran out into the streets.

It was also felt in the departments of Quindio and Tolima.

Colombian seismologists said the quake, which was at a depth of less than 30km, had a reading of 6.5 on the Moment magnitude scale.

The United States Geological Survey, reporting on the same event, measured the quake at 6.7 on the same scale.