A shallow 5.5-magnitude quake struck western Indonesian early today (Saturday), the US Geological Survey said, but no tsunami warning was issued and there were no immediate reports of damage.

The quake struck at 02:24 am (00: 54 IST) off the Mentawai islands at a depth of just one kilometre, 209 kilometres west of Bengkulu on Sumatra island, the USGS said.