Police today looked for the cause of a fire in Tokyo's entertainment district that killed 44 people but said there was no evidence the blaze had been started deliberately.
Four of the dead from Japan's worst fire tragedy in decades had yet to be identified but all of the victims appeared to be Japanese, police said.
Newspapers said violation of fire codes in the gambling and sex clubs crammed into the Shinjuku district's slender pencil buildings was rife.
"The probe is still going on and we are looking into all possibilities including arson. But we won't know the cause until the the results are out and that will take some time", a Tokyo police spokeswoman told reporters.
A team of some 70 policemen and fire officials was involved in the investigation and officials from a gas company were also helping.
A gas leak and explosion were initially believed to have been the cause of the fire. Investigators found a broken gas pipe and a gas meter which had come off the pipes, but domestic media said officials now doubted there had been a gas leak.
"Is it possible for no one to smell gas when the room is full of it to ignite an explosion?" the Asahi Shimbun daily quoted a gas company technician as saying, referring to how survivors had said that they had not smelled gas.
Experts said in addition to the structure of the building, whose floors were only around 80 square-metres, violation of the fire code had exacerbated the tragedy.
They don't have the money to spend on disaster prevention, especially after the economy has worsened. Many tenants leave their sprinklers unfixed, the Yomiuri Shimbun daily quoted a real estate agent specialising in the Shinjuku area as saying.
Fire officials said the four-storey building had only one small staircase illegally crowded with lockers and most of the windows were covered by plastic billboards to shield customers from the public eye.
The second and third floors were not equipped with emergency ladders, in violation of fire laws, and fire doors did not work properly, officials said.
Fire investigators had inspected the building two years ago and found numerous safety code violations, but they had not been dealt with, officials said.