Up to 23 feared dead in Japan quake

Up to 23 people were feared dead on Thursday after a major earthquake in Japan, with four bodies now pulled out from the tangled wreckage of a shopping mall ripped apart by a suspected massive gas explosion.

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.