A medium intensity earthquake struck southwestern Mexico early yesterday morning, scaring residents already shaken by a powerful quake two days earlier, though there were no immediate reports of casualties or damage.

The US Geological Survey said its magnitude was 5.9 and it struck at a depth of 40.2 kilometers (25 miles), some 32 kilometers (20 miles) northeast of the town of Santa Catarina Mechoacan in Oaxaca state at 0657 GMT.

"So far, no impact has been reported," the country's Civil Protection agency tweeted.

President Enrique Pena Nieto tweeted that the agency was in contact with local authorities.

A 7.2-magnitude quake shook the same region on Friday evening.

No one was killed by the seismic event but a helicopter carrying politicians to near the epicenter later crashed, killing 14 people on the ground.