Il Nuovo Postiglione - Up to 23 feared dead in Japan quake

The Kumamoto disaster management office's latest tally put fatalities at 17 and those without vital signs at six, with five more in critical condition two days after the 7.1-magnitude tremor.

Hundreds of rescue workers were meanwhile battling for another day to reach possible survivors in the remains of the Aeon shopping mall in Kashima in the Kumamoto region of southwestern Japan.

At the mall, "we have pulled out 10 people. Of them, four were confirmed dead. Another is without vital signs. Another five have suffered severe and minor injuries", an official from Kumamoto's disaster management office told AFP.

Tuesday's tremor caused widespread damage on the island of Kyushu, flattening homes, damaging bridges, triggering fires and leaving tens of thousands of residents without power and water.

A string of aftershocks have shaken the area since the initial quake, further rattling locals in stifling summer temperatures, forecast to hit at least 35C later in the day and a heatstroke warning issued.

The shopping mall was evacuated after the earthquake but around 50 minutes later the facility was gutted by a massive blast with an unknown number of employees still inside.

Businessman Fumihiko Matsuura, 56, said he had watched the latest "Toy Story" movie at the mall only a week or so ago.

"I was here. I was just here," he told AFP. "It's like I narrowly escaped the danger."

Footage from inside showed rescue workers in orange overalls and white helmets picking their way through a mass of twisted steel, dangling cables and chunks of ceiling.

Five people were also confirmed killed and four others were unaccounted for at the Nippon Paper Industries factory in Yatsushiro city, where part of a red-and-white smokestack collapsed, a government official told AFP on Wednesday.

- Utilities disrupted -

As of Thursday morning, some 22,670 households and facilities still had no power. Around 84,000 homes were suffering water disruptions as of Wednesday.

TV footage showed people queueing for petrol and drinking water.

The US Geological Survey measured the quake at 6.8, lower than Japan's reading of 7.1.

Japan is one of the world's most seismically active countries, sitting on top of four major tectonic plates along the western edge of the Pacific "Ring of Fire".

Kumamoto itself was hit by two devastating earthquakes in 2016, which killed 273 people and injured more than 2,800.

The archipelago, home to around 125 million people, typically experiences hundreds of jolts every year and accounts for about 18 percent of the world's earthquakes.

Japan is haunted by the memory of a massive 9.0-magnitude undersea quake in 2011, which triggered a tsunami that killed or left missing around 18,500 people and wrecked the Fukushima nuclear plant.

M.Costa--INP