Rescuers used diggers and heavy machinery to clear debris and search for survivors yesterday after a magnitude 6.9 earthquake killed at least 98 people on Indonesia's resort island of Lombok, prompting an exodus of tourists.

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 was cleared away after the second powerful quake in a week.

Power and communications were severed in some areas, with landslides and a collapsed bridge blocking access to areas around the quake epicentre in the north - forcing rescue teams to bring in the heavy machinery.

The military said it would send a ship with medical aid, supplies and logistics support.

Indonesia sits on the geologically active Pacific Ring of Fire and is regularly hit by earthquakes. In 2004, the Indian Ocean tsunami killed 226,000 people in 13 countries, including more than 120,000 in Indonesia.

Officials said more than 2,000 people had been evacuated from the three Gili islands off the northwest coast of Lombok, where fears of another tsunami spread among tourists.

Michelle Thompson, an American holidaying on one of the Gilis, described a "scramble" to get on boats leaving for the main island during which her husband was injured.

"People were just throwing their suitcases on board and I had to struggle to get my husband on, because he was bleeding," she said.

Ambulances with sirens blaring raced along the coast from north Lombok, but BNPB spokesman Sutopo Purwo Nugroho said emergency units in its hospitals were overflowing and some patients were being treated in parking lots.

The main hospital in the town of Tanjung in the north was severely damaged, so staff set up about 30 beds in the shade of trees and in a tent on a field to tend to the injured.

A boy with a heavily bandaged leg wailed in pain, an elderly man wore a splint improvised from cardboard strips of cardboard on a broken arm, and some hurt by falling debris still had dried blood on their faces.

BABY BORN

The Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) said more than 120 aftershocks were recorded after Sunday evening's quake.

A man is wheeled past a damaged wall to a makeshift ward set up outside a hospital in Lombok. Photo: Reuters/AFP

Lombok had already been hit on July 29 by a 6.4 magnitude quake that killed 17 people and briefly stranded several hundred trekkers on the slopes of a volcano.

At magnitude 6.9, Sunday's quake released more than five times the energy of the earlier one, the United States Geological Survey website said.

The tremor was powerful enough to be felt on the neighbouring island of Bali where, BNPB said, two people died. The first quake was also felt on Bali.

Despite it being a popular tourist destination, no foreigners were recorded among the dead, BNPB spokesman Nugroho told a news conference. Some 236 people were injured and more than 20,000 people had been displaced, he said.

"We have yet to ask for help from the international(community). But if there's any friendly country who wants to offer help, please do," Nugroho said.

The United Nations has offered to support any ongoing rescue and relief efforts if required.

Among the devastation, the Indonesian Red Cross said on Twitter it had helped a woman give birth at a health post after the quake. One of the names she gave the baby boy was "Gempa", which means earthquake.

Among those displaced were residents of a northern village called Mentigi, who fled to nearby hills. Blue tarpaulins dotted the landscape as people prepared to spend the nights outdoors because of aftershocks or because their homes were destroyed.

"We are getting some aid from volunteers, but we don't have proper tents yet," said a 50-year-old villager sheltering with his wife and children, who gave his name only as Marhun.

Sengiggi, a seaside tourist strip on Lombok, wore an abandoned look. Amid collapsed homes, most hotels seemed to have shut, and beaches were deserted. The few restaurants left open were rationing food.

Long lines formed at the airport of Lombok's main town, Mataram, as foreign visitors cut their holidays short. BNPB said 18 extra flights had been added for leaving tourists.

"I was at the rooftop of my hotel and the building started swaying very hard ... I could not stand up," said Gino Poggiali, a 43-year-old Frenchman, who was with his wife and two children at the airport.

His wife Maude, 44, said the family was on Bali for the first quake and Lombok for the second.

"This is it for me in Indonesia. Next time we will stay in France, or somewhere close," she said.

Dutch tourist Marc Ganbuwalba injured his knee in a stampede of diners from a restaurant after the quake.