A strong earthquake registering a 6.9 magnitude has struck off the coast of Mexico, but there were no immediate reports of damage inland.

The US Geological Survey (USGS) said the quake was centred 78 miles (127km) northeast of Guerrero Negro. The epicentre was 6.2 miles down.

The USGS initially reported the quake had a magnitude of 7.1 but the figure was revised down to 6.9. No tsunami warning was issued.

The tremor followed a 6.4 magnitude quake which struck a sparsely populated area in the western state of Michoacan, causing tall buildings to sway more than 200 miles away in Mexico City. Again, there were no reports of casualties.

The earthquake had a magnitude of 6.9 (USGS)
The earthquake registered a magnitude of 6.9 (USGS)

A powerful 7.4-magnitude quake hit southern Mexico on 20 March, but this was not an aftershock of that one, USGS geophysicist Dale Grant said.

That earthquake was felt strongly in the nation's capital, and it damaged hundreds of homes and killed at least two people near the border between Guerrero and Oaxaca states. Mexico's seismological service said that quake has been followed by close to 400 aftershocks, including one of magnitude 6.0.

The latest Mexico quakes came as Indonesians dealt with the aftermath of another earthquake and tsunami scare when a tremor measuring 8.6 struck off the coast of Aceh province 20 miles beneath the ocean floor. The aftershock registered a magnitude of 8.2 off the western coast of Sumatra.

A tsunami warning was put in place across most of the Indian Ocean but no major damage or casualties were reported.