Indonesia issued a tsunami warning, urging people to evacuate to higher ground after an earthquake of magnitude 6.8 struck off the coast of its island of Sulawesi.

Indonesia suffered its highest death toll in natural disasters in more than a decade last year, following two major tsunamis and several earthquakes.

More than 3000 people were killed in Palu, also in Central Sulawesi, the site of Friday's earthquake.

"It is clear that the quake has tsunami potential," said geophysics agency spokesman Taufan Maulana. "Residents are advised to evacuate as soon possible."

The agency is monitoring for high waves as the quake had the potential to trigger a tsunami, it added.