Indonesian authorities have started to immunise thousands of earthquake survivors against measles.

Helicopters are also sweeping the devastated region on Java island to check for isolated victims.

Health Minister Siti Fadillah Supari said the government was evacuating patients from hospitals in the immediate area to more distant cities to relieve overcrowding.

"For now (the hospitals) are starting to get tidy and we have penetrated isolated areas using mobile clinics ... helicopters dispatch food while airlifting the patients. The supply of medicine is also flowing," she told Reuters.

"Today we are continuing to comb (the region) to make sure there are no untouched areas."

The death toll from Saturday's quake has reached 5,846 and around 130,000 are listed as homeless.

So far there were no signs of any outbreaks of disease, but medicines were being sent to affected areas to prevent diseases such as measles and malaria.

The 6.3 magnitude quake, which was centred just off the Indian Ocean coast near Yogyakarta, wrecked some infrastructure like water pipes and pumps. Adding to the challenges of delivering shelter, clean water and food to those in need are the wide area affected and poor roads.

Around the Bantul area hardest hit by the quake, entire villages were destroyed, homes reduced to piles of wood, tiles and tin, and survivors used whatever they could find to construct makeshift tents.

Asian Development Bank President Haruhiko Kuroda said that President Susilo Bambang Yudhoyono's government had learned from the December 26, 2004, Indian Ocean quake and subsequent tsunami that left 170,000 Indonesians killed or missing.

"This time the government was very quick in responding to the need," Kuroda told Reuters, praising the administration for restoring electricity and other utilities quickly.

Dozens of countries ranging from Japan, Australia and the United States to Saudi Arabia and the United Arab Emirates have pledged cash, emergency supplies and personnel, and UN agencies and private international organisations like the Red Cross began moving aid in shortly after Saturday morning's quake.

Much of the aid is being airlifted to the airport of the ancient royal capital of Yogyakarta, the main city in the afflicted area, where Japanese paramedics and US Marines medical personnel are among those who have landed to reinforce government aid and workers.