The Indonesian island of Lombok has been hit by a strong tremor, as the search continues for victims of Sunday's earthquake.
US earthquake monitors said the latest aftershock had a magnitude of 5.9. It brought down some buildings.
Rescue workers are still digging through rubble and trying to get aid to survivors of the earlier, larger quake.
The Red Cross has said that incident, which killed at least 131 people, was "exceptionally destructive".
Some villages had "completely collapsed", said a Red Cross official in Lombok, Christopher Rassi.
The official death toll stands at 131, but local media are reporting figures as high as 347.
The government says more than 1,400 people were injured and more than 156,000 displaced.
The national disaster agency has said all those numbers are likely to increase, as more information comes in and more victims are found.
The new tremor hit off the north-west coast of Lombok, sending people running into the streets in panic.
Indonesia's meteorological agency put the magnitude at 6.2. No tsunami warning has been issued.
Disaster agency spokesman Sutopo Purwo Nugroho classified it as an aftershock. A British tourist on nearby Bali told the BBC that it had been felt there, causing people to leave their hotel rooms in the southern resort area of Seminyak.
It is likely to have been the strongest of the more than 340 aftershocks in the area since Sunday.
Emergency workers are gradually starting to reach more remote areas of Lombok as they continue their rescue missions.
But Mr Sutopo said some areas in the north had still not received any aid.
Lombok is a roughly 4,500 sq km (1,700 sq miles) island east of the slightly larger island of Bali.
Most people live in basic housing in small communities. Tens of thousands are now sleeping out in the open or in the ruins of their homes.
"We are still waiting for assessments from some of the more remote areas in the north of the island, but it is already clear that Sunday's earthquake was exceptionally destructive," said Mr Rassi.
"I visited villages yesterday that were completely collapsed," he added, while other teams in East and North Lombok had reported villages where 75% of homes were damaged.
With hospitals and clinics also affected, many of the injured have had to be treated in the open air or in makeshift clinics.
Sunday's quake came only days after a slightly smaller one, which killed at least 16 people. There are growing concerns that the important tourism industry will be badly hit at what should be a busy time.
Thousands of tourists visiting Lombok - as well as the nearby Gili Islands and Bali - have been evacuated or have chosen to leave since the weekend.
"We've had light earthquakes in the past, but never anything like this," hotel chain owner Marcel De Rijk told Reuters news agency.
"We've lost a lot of bookings and future guests are in wait-and-see mode. I don't think people will choose Lombok anymore this summer."
The quake struck at 19:46 local time (11:46 GMT) on Sunday at a fairly shallow depth of 31km (19 miles).
Indonesia is prone to earthquakes because it lies on the Ring of Fire - the line of frequent quakes and volcanic eruptions that circles virtually the entire Pacific rim.
More than half of the world's active volcanoes above sea level are part of the ring.
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