CHIAYI, TAIWAN (NYTIMES) - Taiwanese prosecutors said that a couple were suspected of setting a fire and negligent homicide after 46 people were killed and dozens of others injured last week in the island's deadliest building blaze in more than two decades.

The prosecutors accused the 51-year-old woman, who was identified only by her surname, Huang, of failing to extinguish an incense coil when she left the 13-storey mixed-used building in the southern port city of Kaohsiung early on Thursday (Oct 14).

The 52-year-old man, surnamed Kuo, was accused of failing to remind Huang to put out the incense.

The unattended coil, which was in her room on the building's first floor, sparked a blaze that quickly engulfed the higher floors, making it difficult for the residents - mostly poorer and older people who had been asleep at the time - to escape.

Authorities zeroed in on the couple, who are partners, on Friday.

Huang was detained after being interrogated, while Kuo was freed on about US$2,000 (S$2,699) bail, prosecutors in Kaohsiung said.

The two have not yet been formally charged.

The fire has raised broader concerns about lax safety standards in the island's ageing structures.

The once-prosperous building in Kaohsiung's waterfront district, built in the 1980s, was partly abandoned and had deteriorated rapidly in recent years.

The blaze also highlighted the lack of support for poor and older people who are desperate for housing and often have no choice but to live in dilapidated buildings.

Among residents it had become known as a "ghost building".

Piles of garbage had accumulated on lower floors and in the stairwells, which fire officials said had accelerated the spread of the fire and impeded rescue efforts.

At the time of the fire, the building was inhabited by squatters, gamblers, sex workers and older and poorer people.

The average age of those killed in the fire was 62.

On Monday, Taiwan's Interior Minister, Mr Hsu Kuo-Yung, ordered local officials to create an inventory of all the island's older buildings within one month, and to complete inspections of the public safety and fire facilities of such structures within three months.

In Kaohsiung alone, at least 34 older buildings have already been identified by the authorities as "high-risk".