South Korean police have arrested the owner and the manager of a building where 29 people died in a fire last week, accusing the pair of multiple safety lapses, including blocked exits and malfunctioning sprinkler systems.

On Thursday a fire ripped through an eight-story high rise in the small city of Jecheon. At least 20 of the victims were women who were overcome by toxic fumes in a second-floor sauna.

Jecheon police have only identified the owner by his last name of Lee, and the manager by his last name of Kim.

Both men are in custody in Jecheon after being arrested on Sunday, police announced Tuesday.

Lee faces two charges of violating fire safety regulations and committing involuntary homicide by professional negligence, while Kim also faces the involuntary homicide charge.

If convicted of involuntary homicide, Lee and Kim could face up to five years in prison or 20 million won (US$16,000) in fines.

A survivor dangles from a windowsill as he waits for rescue from the burning building on Dec 21, 2017. - REUTERS
"The sprinkler system on the building's first floor did not work properly when the fire erupted," a police detective, who asked not to be named as he was not authorized to speak on an ongoing investigation, told Reuters. "If the sprinkler system worked, the fire probably would not have spread as fast as it did."

Photos released by the Yonhap news agency showed a smoke-stained stairwell and a fire exit filled with shelves and supplies on the second floor, where most of the deaths occurred.

"The emergency exit on the building’s second floor was blocked by iron shelves and other miscellaneous items," the detective confirmed.

Officials are still investigating the cause of the conflagration.

According to police, both Kim and Lee had denied reports they were trying to remove ice on the ceiling of the first floor, where the fire appeared to have originated, but later changed their statements after police confronted them with evidence.

The Korea JoongAng Daily newspaper reported on Tuesday that Lee had at one point told police he did not alert the women in the sauna because they were undressed, however, the police detective told Reuters he could not confirm that as investigations were ongoing.

Anger mounted over the weekend at reports of shoddy construction, broken doors, blocked roads and other problems that may have contributed to the deaths.

Yonhap photos of the scene showed parked cars surrounding the building, with some witnesses saying that combined with narrow roads to delay the response by fire trucks.

A bill was introduced in March calling for doubling the penalty for illegal parking on a fire engine access road but it is still pending, according to the National Assembly’s bill tracking archive.

Visiting the scene on Friday, President Moon Jae-in promised a full investigation.

"The government as a whole will thoroughly probe this accident's cause and process of response, and although after the fact, the investigation and measures will be such that, at least, there will not be lingering deep sorrow," he said.

On Monday, a separate fire at a construction site at an apartment complex south of Seoul killed one person and injured 14 others, according to Yonhap.