Rescue workers found scenes of destruction across the north of Indonesia's resort island of Lombok on Monday after a magnitude 6.9 earthquake killed at least 91 people and prompted an exodus of tourists rattled by the second powerful quake in a week.

The National Disaster Mitigation Agency (BNPB) said it expected the death toll to rise once the rubble of more than 13,000 flattened and damaged houses is cleared away, but a lack of heavy equipment meant this would take time.

Power and communications were cut in some areas of Lombok, with landslides and a collapsed bridge hampering access to the north. The Indonesian military said it was sending in a ship with medical aid, supplies and logistical support.