TOKYO (Reuters) - The desperate search for survivors intensified on Sunday (April 17) in the splintered remains of buildings destroyed by Japan's deadly earthquake and the authorities ordered nearly a quarter of a million people from their homes amid fears of further quakes.

A 7.3-magnitude tremor struck early on Saturday morning, killing at least 32 people, injuring about a thousand more and causing widespread damage to houses, roads and bridges.

It was the second major quake to hit Kumamoto province on the island of Kyushu in just over 24 hours. The first, late on Thursday, killed nine people.

Rescuers on Sunday searched for dozens of people feared trapped or buried alive, while survivors queued for scarce supplies of food and water.

In the village of Minamiaso, 11 people remain "out of contact", said public broadcaster NHK. Rescuers pulled 10 students out of a collapsed university apartment in Minamiaso on Saturday.

"In Minamiaso, where the damage is concentrated, there may still be people trapped under collapsed buildings, so we are focusing our attention and rescue and search efforts in this area," Chief Cabinet Secretary Yoshihide Suga told reporters.

Overnight, rescuers digging with their bare hands dragged some elderly survivors, still in their pyjamas, out of the rubble and onto makeshift stretchers made of tatami mats.

Prime Minister Shinzo Abe said the United States had offered to send in troops to help, but Japan was coping with the disaster.

"The Self Defense Force, police and fire-fighters have been working to rescue people but there are still missing people. The government will further deploy all possible means by expanding the troop size to 25,000," Mr Abe told reporters.

Factories for companies including Sony, Honda and Toyota halted production as they assessed damage in the region, an important manufacturing hub in Japan's south.

Toyota Motor Corp said it would suspend production at plants across Japan after the quakes disrupted its supply chain. Electronics giant Sony Corp said its Kumamoto plant, which makes image sensors for Apple and others, would remain suspended.

All commercial flights to the damaged Kumamoto airport were cancelled and Japan's bullet train to the region suspended. Expressways are closed in wide areas because of landslides and cracks in the road surface, hindering supplies of water and food reaching survivors.

Three nuclear plants in the region were unaffected by the quake, but the Nuclear Regulation Authority said it will hold an extraordinary meeting on Monday to discuss the situation.

Heavy rains fuelled worries of more landslides and with hundreds of aftershocks and fears of more quakes, thousands spent the night in evacuation centres.

"It's full in there. There's not a inch to sleep or even walk about in there. It's impossible in there," a resident of Mashiki town said outside an evacuation centre.

Another survivor said the cleanup would be extensive. "I can't even imagine when we can start the recovery process. My home is a mess, I don't know what to do next. And all these people affected."

Firefighters handed out tarpaulins to residents so they could cover damaged roofs, but many homes were simply deserted.

Around 62,700 households were without electricity, water supplies had been disrupted to more than 300,000 homes and some areas had no gas, said NHK.

More than 110,000 people have been evacuated from the Kumamoto area, said Kyodo. Troops set up tents for evacuees and water trucks were being sent to the area while television footage showed people stranded after the fall of a bridge being rescued by helicopters.

The indiscriminate nature of the destruction saw some houses reduced to piles of splintered timber and smashed roof tiles while neighbouring homes were left standing.

"I felt strong shaking at first, then I was thrown about like I was in a washing machine," said a Tokai University student who remains isolated in the village of Minamiaso.

About 422,000 households were without water and 100,000 without electricity, the government said.

NHK said around 240,000 people had received evacuation orders across the affected region amid fears of landslides.

NHK showed footage of people stranded after the fall of a bridge being rescued by helicopters.

Troops set up tents for evacuees and water trucks were being sent to the area while television footage showed people stranded after the fall of a bridge being rescued by helicopters.

The National Police Agency said 32 people had been confirmed dead in Saturday's quake. The government said about 190 of those injured were in a serious condition.

On the other side of the Pacific, Ecuador was also struggling with the aftermath of a major 7.8 quake which hit on Saturday, killing at least 28 people and sparking a tsunami warning.

Both Japan and Ecuador are on the seismically active "ring of fire" around the Pacific Ocean.

Japan has building codes aimed at helping structures withstand earthquakes.

A magnitude-9 quake in March 2011 north of Tokyo touched off a massive tsunami and nuclear meltdowns at Fukushima, contaminating water, food and air for miles around. Nearly 20,000 people were killed in the tsunami.

The epicentre of Saturday's quake was near the city of Kumamoto and measured at a shallow depth of 10km, the United States Geological Survey (USGS) said. The shallower a quake, the more likely it is to cause damage.

However, no irregularities were reported at three nuclear power plants in the area, a senior government official said.

The city's 400-year-old Kumamoto Castle was badly damaged, with its walls breached after having withstood bombardment and fire in its four centuries of existence.

Bank of Japan Governor Haruhiko Kuroda, speaking at a G20 event in Washington, said it was too early to assess the economic impact but bank operations in Kumamoto were normal.

The USGS estimated there was a 72 per cent likelihood of economic damage exceeding $10 billion, adding that it was too early to be specific. Major insurers are yet to release estimates.

Electronics giant Sony Corp said a plant producing image sensors for smartphone makers would remain closed while it assessed the damage from the quakes. One of its major customers is Apple which uses the sensors in iPhones.

Operations at Toyota Motor Corp and Nissan Motor Co were also disrupted.

The region's transport network suffered considerable damage with one tunnel caved in, a highway bridge damaged, roads cut or blocked by landslips and train services halted, media reported. Kumamoto airport was closed.

There have been 378 aftershocks of at least level 1 on the Japanese scale since Thursday's shock, NHK reported.