An overnight fire tore through a building in the southern Taiwanese city of Kaohsiung on Thursday, killing 46 people and injuring dozens of others, officials said.

The blaze broke out in the 13-storey, mixed-use building in the small hours of Thursday morning, according to officials, raging through multiple floors before firefighters finally got it under control.

"The fire caused 41 injuries and 46 deaths," Kaohsiung's fire department said in a statement to reporters.

Pictures published by Taiwan's official Central News Agency showed smoke billowing out of the building's windows as firefighters desperately tried to douse the flames using extendable hoses.

The city's fire department said it sent more than 70 trucks to tackle the blaze.

As daylight broke the sheer scale of the fire became clear, with every floor of the building visibly blackened.

Most of the deaths occurred on floors seven to 11, which housed residential apartments, fire officials said. 

The first five floors were for commercial use but were unoccupied.

A constable at the Kaohsiung police department told AFP the building was 40 years old and mostly occupied by low-income residents.

Survivors had estimated about 100 people lived in the apartment, the constable added, giving only his surname Liu.

Officials had not yet ruled out arson, he added. Forensics teams were on site and further searches of the building were planned before sunset.

As an island frequently battered by earthquakes and typhoons, Taiwan has strict building codes and a generally good safety record.

But older buildings still pose risks.

Some of the highest death tolls in recent earthquakes have come when older buildings collapsed, with subsequent investigations occasionally showing their designs were not up to code.