6.2-magnitude quake off Sumatra, Indonesia

JAKARTA (Reuters) - A strong earthquake has struck Indonesia's Nias island west of Sumatra island, causing panic and some damage, but no reports of casualties, an official at the country's meteorology agency said on Wednesday.

The magnitude 6.2 quake struck just after midnight, 172 km west of Sibolga at a depth of 12 km, the U.S. Geological Survey said in a bulletin on its Web site.

"The epicentre was on Nias island and caused panic, as well as cracking several houses, although there were no immediate reports of casualties," said Andri Gsetiaji at the meteorology agency in Jakarta.

A weaker aftershock later struck about 80 km southwest of Gunungsitoli, the capital of Nias, the official added.

Indonesia suffers frequent earthquakes since it lies on an area of intense seismic activity where a number of tectonic plates collide.

The Pacific Tsunami Warning Center said there were no immediate tsunami warnings or watches in effect.