CIANJUR: Driving rain and the danger of landslides disrupted work of Indonesian rescue workers searching on Wednesday for survivors of an earthquake that killed 271 people, with an official warning that time was running out for anyone trapped in rubble.

Monday's 5.6-magnitude quake caused extensive damage in the town of Cianjur, in mountains about 75 km (45 miles) south of the capital, Jakarta. 40 people remained missing.

Recovery efforts on a rainy Wednesday focused on Cugenang, one of the worst-hit districts, where at least one village is believed to have been buried under a landslide.

Helicopters were due to drop food and water to two villages that could not be reached by road, said Henri Alfiandi, chief of the search and rescue agency.

He said the chances of anyone trapped in rubble surviving three days after the quake were increasingly slim but the danger of aftershocks triggering more landslides down rain-soaked slopes had delayed his teams.

"Because the quake was quite strong and raining, we feared there would be landslides. But we have continued the evacuation process now," Henri told Reuters.

Ai Nurjanah, 48, said she was trapped under fallen concrete for about 15 minutes after the quake, while shielding her 4-year-old daughter under her. They were having a having a nap when the quake hit.

"I keep shouting for help until I ran out of voice. My daughter was crying, 'Mama, it's dark, I can't breathe'," she told Reuters while waiting to be treated for her injuries at a hospital.

Authorities were working to bring in more heavy machinery to clear the landslides. Around 6,000 rescuers have been dispatched, said the disaster mitigation agency.

Officials said there had been more than 170 aftershocks including a 3.9 magnitude one on Wednesday afternoon.

As the search continued, rescuers pulled out a 5-year-old boy from the rubble, who had survived because he was protected by a mattress.

In a video of the rescue posted by a local fire department, Azka, who had been trapped for two days, appeared conscious and calm as he was lifted to safety.

"(Azka) is fine now, not wounded. The doctor said he's only weak because he's hungry," said his relative Salman Alfarisi, 22, while holding Azka's hand at a makeshift tent in the hospital parking lot, adding his mother had died.

"He wants to go home now. He's been asking for his mother while sleeping."

At a Cianjur hospital, patients were being treated outside in tents due to the fear of aftershocks, a member of staff said.

Health Minister Budi Gunadi Sadikin said there was an urgent need for extra help for patients in quake-damaged hospitals.

Indonesia is one of the world's most earthquake-prone nations, regularly recording strong earthquakes offshore where fault lines run.

But Monday's quake was so deadly because it struck a densely populated area at a shallow depth of just 10 km (6 miles).

Poor building standards led to many deaths, officials said.

President Joko Widodo called for earthquake-proof housing to be included in reconstruction efforts when he visited the disaster zone on Tuesday.