An earthquake of 6.2 magnitude struck off the Indonesian island of Lombok on Thursday, the United States Geological Survey (USGS) said.

The USGS also said that the earthquake was under sea, at a depth of 29 km. The quake hit at a distance of 234km from the popular holiday island of Lombok, Indonesia.

Sutopo Purwo Nugroho, a spokesman of Indonesia's Disaster Mitigation Agency, told the Straits Times the earthquake was a strong one and the tremors lasted for three to four seconds. However, there were no immediate reports of casualties or damage and it did not trigger a tsunami alert.

A witness in Lombak said, "The quake went on for quite a while. People ran out from houses in panic."

Tourists on the Indonesian resort island of Bali were also scared because of the quake.

Indonesia's disaster agency said the officials are trying to check if there was any impact in any place.

Indonesia is positioned on the Pacific "Ring of Fire", which is known for collision of tectonic plates.