ISLAMABAD, Pakistan - A strong earthquake struck parts of southwestern Pakistan early Wednesday, killing at least 31 people.

The quake struck just after 4 a.m. in Balochistan, an impoverished province bordering Afghanistan. It had a preliminary magnitude of 6.4, the U.S. Geological Survey reported.

Balochistan police chief Asif Nawaz Khos said at least 31 people had been killed, while a local mayor said many houses were damaged.

The quake was centred southwest of the capital, Islamabad.

Pakistan is prone to violent seismic upheavals.

In October 2005, a magnitude-7.6 quake devastated Kashmir and northern Pakistan, killing about 80,000 people and leaving hundreds of thousands homeless.

Balochistan is home to a long-running separatist movement, but is not considered a major battleground in the fight against Taliban insurgents that plague other border regions.