The aftershock occurred around 24 hours after yesterday's 7.8-magnitude quake that claimed the lives of at least 10,000 people.

Monday's quake, which struck at 2.28 p.m. (06:28 GMT), was the worst to hit the country in more than three decades, and affected eight provinces, devastating buildings and infrastructure, leaving thousands of people buried alive under rubble.

Some 60,000 people are said to be unaccounted for near the epicenter of the quake, which was located some 60 miles (96 km) northwest of Chengdu.

An estimated 17,000 Chinese soldiers and 34,000 military are involved in the ongoing disaster relief operation.