UPDATE 1-Strong quake hits Indonesia, no reports of damage

(Adds details, USGS revises magnitude to 6.3)

JAKARTA, June 20 (Reuters) - A powerful earthquake struck Indonesia early on Thursday, 248 km west of Jayapura, Irian Jaya, in the province of West Papua, the U.S. Geological Survey (USGS) said.

USGS said the quake had a magnitude of 6.3, revising its initial estimate of the magnitude from 6.5.

There were no reports of damage so far and Indonesian authorities said there was no risk of a tsunami.

The quake, which hit in an area that is sparsely populated, had a depth of 12 km, USGS said, revising its initial estimate of a depth of 10 km. (Reporting by Gayatri Suroyo; Editing by Alison Williams and David Evans)