SINGAPORE (REUTERS, AFP) - An earthquake of magnitude 6.2 struck off the Indonesian island of Lombok on Thursday (June 9), the United States Geological Survey said.

The undersea quake, at a depth of 29km, hit at a distance of 234km from the popular holiday island of Lombok, it added.

There were no immediate reports of casualties or damage.

The quake was strong, with tremors lasting for three to four seconds, but did not trigger a tsunami alert, said Sutopo Purwo Nugroho, a spokesman of Indonesia's Disaster Mitigation Agency (BNPB).

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

The quake also briefly startled tourists on the Indonesian resort island of Bali.

Indonesia's disaster agency said officials were checking to see if the quake had any impact.

Indonesia experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire", where tectonic plates collide.