THE death toll from Tuesday's Italian bridge disaster has reached 42, including three children.

First responders said 16 people had been injured all but one of whom remain in hospital. Twelve of those hurt are still listed as seriously ill, or "code red".

Rescuers said they have heard no sign of life since Tuesday evening. "With every hour that passes it gets ever more difficult to find anyone alive but we continue to hope and to dig," said local civil protection official Giacomo Giampedrone. 

Genoa's chief prosecutor sounded a warning that there would be consequences for the tragedy and formally opened an investigation in to multiple homicides. Francesco Cozzi said: "This was not fate, this was human error."

As rescue efforts continued, huge political pressure was put on the private company responsible for Italy's highway infrastructure, much of it constructed during the country's boom years in the 1950s and 1960s.

Transport minister Danilo Toninelli called for the resignation of executives at Autostrade per L'Italia, the motorway operating firm. He also announced that he had begun a procedure of stripping the firm of its franchise to run the system, according to the newspaper Il Fatto Quotidiano. He said: "If they are not capable of managing our motorways then the state will do so."

Witnesses reported hearing a roar as the 45-metre bridge collapsed in torrential rain during midday traffic on the eve of a major holiday that sees most Italians abandoning cities for beaches and mountains.