Tuxtla Gutiérrez, Mexico (AFP) - A strong 6.6-magnitude earthquake rattled southern Mexico on Thursday (Dec 17), prompting people to evacuate buildings and schools, while the quake was also felt in neighbouring Guatemala.

The 94km deep quake struck at 1.49pm local time in the state of Chiapas, some 7km east of the coastal town of Tres Picos, according to the US Geological Survey.

Mexico's civil protection coordinator, Luis Felipe Puente, said state and municipal officials did not report any damage "for the moment." The quake was strongly felt in Chiapas, as buildings and schools were emptied in the state capital, Tuxtla Gutierrez.

Puente said on Twitter the earthquake was also felt "moderately" in neighbouring Oaxaca state and "strongly" in Tabasco.

Mexico City Mayor Miguel Angel Mancera said it was "lightly felt" in the mega-capital of 21 million people but no immediate damage was reported.

The state-run oil firm Pemex said it was operating "normally" in the states of Chiapas, Campeche and Tabasco, but it evacuated its administrative buildings in Tabasco's capital, Villahermosa, as a precaution.

USGS changed its measurement twice after initially calculating a 6.6-magnitude. It downgraded it to 6.4 before revising it back to 6.6.