The fire, which started on the upper floors of the tower on the southern outskirts of Milan, spread to the rest of the building owing to what experts described as the “chimney effect”.

According to the authorities, about 20 residents suffered slight smoke inhalation. Dozens of ambulances and fire engines were at the scene. The building houses about 70 families, who were being contacted in an effort to make sure no one was missing. All the residents who were in their apartments when the fire broke out – about 30 people – were safely evacuated.

Officials said the flames had spread through the cladding on the facade, which was supposed to have been fire-resistant.

Milan’s mayor, Beppe Sala, wrote on Facebook: “What was clear from the start was that the building’s outer shell went up in flames far too quickly, in a manner reminiscent of the Grenfell Tower fire in London a few years ago. The tower was built just over 10 years ago and it is unacceptable that such a modern building should have proved totally vulnerable.”

Angelo Lucchini, a professor of technical architecture at the Polytechnic University of Milan, stated, “The facade of the building was built with combustible materials. Unfortunately, there is no law that prohibits it.”

Prosecutors in Milan have launched an investigation to determine the cause of the fire. According to Carlo Sibilia, an interior ministry official in Rome, the rapid spread of the flames was due to the thermal covering of the building.

Authorities now fear the building is at risk of collapse, owing to the high temperatures that could have melted the steel columns.

The 60-meter-high building in Milan was designed to look like the keel of a ship. It included an aluminium sail on its roof, which burned after the blaze, falling in pieces to the street.