An investigative commission released the report during an open session of parliament today.
It detailed the reasons Plasco, a high-rise building in Tehran, became engulfed in flames in January, killing 26 people, including 16 firefighters. More than 230 were injured.
The report said the building's electrical and heating systems and fire safety regulations were not up to standard and contributed to the building fire and collapse.
The fire and subsequent building collapse was the worst such disaster in Tehran since 2005, when a blaze at a historic mosque killed 59.