A major 6.5-magnitude earthquake struck Mexico on Saturday with officials reporting two deaths, as the quake was strongly felt in the capital Mexico City and southern Guerrero state.

The temblor occurred at 7:47 pm (0147 GMT Sunday) about 166 kilometers (103 miles) southwest of Mexico City, at a depth of about 65 kilometers, according to US Geological Survey.

The epicenter was located 133 kilometers north of the large beach resort city of Acapulco, on the country's Pacific coast.

The death toll included an 11-year-old boy in the town of Iguana and another fatality on a road near Paloblanco, said Arturo Martinez, a spokesman for the government of Chilpancingo in Guerrero state.

The Pacific Tsunami Warning center said no destructive Pacific-wide tsunami was expected.

USGS originally measured the quake at a stronger 6.7 magnitude, but downgraded it to 6.5 about an hour later.

Mexican President Felipe Calderon issued a comment through his official Twitter account, saying there was "no major damage reported at the time, however the reports are preliminary.

"If you are aware of damage, please tell us," he added.

Some areas of the capital, where thousands of pilgrims were congregating for the feast of Our Lady of Guadalupe, experienced temporary electricity blackouts, and cell phone networks quickly became saturated.

The quake sent hundreds of people celebrating upcoming Christmas festivities at the Telephone Workers Union rushing into the streets, an AFP reporter witnessed.

Much of Mexico lies on the Pacific Ring of Fire, where most of the world's earthquakes and volcanic eruptions occur.

A historic 8.1-magnitude quake struck off Mexico's Pacific coast in 1985, and while it was centered some 350 kilometers from Mexico City, it devastated the capital, killing at least 10,000 people.