JAKARTA - A moderate 5.2-magnitude earthquake struck off Indonesia's Sumatra island on Tuesday, the US Geological Survey said.

The quake hit at 5:15 pm (1015 GMT), 185 kilometres (115 miles) southwest of the city of Sibolga in North Sumatra province, the USGS said. It was 35 kilometres deep.

There were no immediate reports of damage and the Indonesian meteorology and geophysics agency had not issued a tsunami warning.

The agency clocked the quake at 5.5 on the Richter Scale.

Indonesia was the nation worst hit by the quake-triggered Asian tsunami in December 2004 that killed 168,000 people in the country's Aceh province.

The Indonesian archipelago sits on the so-called Pacific Ring of Fire, where continental plates meet and cause frequent seismic and volcanic activity.

- AFP /ls