Indonesia issued the sixth tsunami warning on Thursday evening after a 6.8-magnitude aftershock rocked Bengkulu province in Sumatra Island, according to the Meteorology and Geophysics Agency.

The aftershock struck at 23:09 Jakarta time (1609 GMT) with epicenter at 121 kilometers southwest Lais town in northern part of the province and 10 kilometers under sea bed, an official of the agency said.

"The shock is potential for tsunami," said an official of the agency.

The powerful main shock with magnitude of 7.9 rocked Bengkulu province on Wednesday afternoon.

Until Thursday evening, powerful and moderate tremors frequently occurred in the area, according to the meteorology agency.

(Xinhua News Agency September 14, 2007)