SUBANG - A magnitude-6.5 earthquake rocked the sea north of Indonesia's Java island on Wednesday (Oct 19), according to the United States Geological Survey (USGS).

The tremblor was recorded 120km north-east of Subang, West Java at 7.25 am local time, the USGS reported.

Indonesia's National Disaster Management Agency (BNPB) said tremors were felt for up to eight seconds in some areas in northern Banten, West Java and Jakarta but there have been no reports of casualties and damage to property.

BNPB spokesman Sutopo Purwo Nugroho said on Wednesday that the deep epicentre of the quake - recorded at 654 km below the sea floor - helped minimise the impact of the magnitude 6.5 earthquake.

"But people must still be prepared for an earthquake, which could occur anytime," he added.