The US Geological Survey revised its estimate of the magnitude of an earthquake in Mexico yesterday from six to 5.6.
The quake struck about 255 kilometres south of Mexico City shortly before noon local time (1700 GMT), the USGS said on its website. The temblor rocked buildings but there were no initial reports of significant damage or injuries.
The quake came as the Mexican capital was already at the centre of a swine flu outbreak that has killed up to 149 people.