BANDA ACEH: A moderate earthquake struck off Indonesia's Sumatra island Tuesday, US seismologists said, sending people running in fear from Aceh province's parliament.

The 5.1-quake hit at 10:24 am (0324 GMT) at a depth of around 42 kilometres (26 miles), 80 kilometres southwest of the provincial capital Banda Aceh, the US Geological Survey said.

“The epicentre was located in the sea and was felt by people in Banda Aceh,” said Arif Achir of Indonesia's meteorology and geophysics agency, adding there was no tsunami threat or immediate reports of damage.

An AFP correspondent said the quake lasted around 45 seconds, sending people running from parliament and children from classrooms.

Aceh province was shaken last Wednesday by two huge earthquakes that triggered an Indian Ocean-wide tsunami alert.

At a magnitude of 8.6, the first of the two quakes was the strongest to hit since the 2004 Indian Ocean tsunami that killed 170,000 in Aceh. No major damage was reported.