JAKARTA - INDONESIA on Thursday issued a third tsunami warning in the past 24 hours, as a strong aftershock of a 7.7 magnitude rattled Sumatra island, the meteorology office said.

The quake hit at 6.49am (7.49am Singapore time), about 140 kilometres south-west of the town of Jambi, in the central part of Sumatra, at a depth of 24 kilometres, the agency said by short text message.

'Tsunami potential, to be forwarded to the public,' the message said.

Tremors were also felt in Singapore.