Twenty people could still be missing in the rubble of the deadly Morandi Bridge collapse in Genoa, the city’s chief prosecutor has said, as hundreds of rescue workers continued to search for survivors on Wednesday.

Genoa chief prosecutor Francesco Cozzi told reporters that “there could be 10 to 20 persons still missing”.

His comments come after a 12-month state of emergency was declared in the Italian city.

The bridge collapsed at about midday on the eve of Italy’s biggest summer holiday. 

Interior Minister Matteo Salvini said that it was difficult to determine exactly how many more potential victims there may still be, as some of those reported missing by loved ones might actually be holidaymakers who reached their destination and had not contacted family or friends in recent days.

Authorities have announced plans for a state funeral for the victims to be held on Saturday morning in the north-western city, with the day designated as one of national mourning. The ceremony will be presided over by Cardinal Angelo Bagnasco, the Genoa archbishop.

About 1,000 emergency workers, including 400 firefighters, are continuing to clear the wreckage and search for survivors after at least 39 people died when the structure collapsed on Tuesday.

An 80-metre section of the Morandi Bridge, including one set of the supports that tower above it, crashed down, sending vehicles plunging nearly 150ft.

Cranes are being used to shift truck-sized chunks of broken concrete as the government reacted furiously towards the viaduct’s operator, Autostrade.

The 51-year-old structure collapsed during torrential rain on Tuesday and dozens of vehicles crashed onto a riverbed, a railway and two warehouses. 

The 1.2km-long bridge was completed in 1967 and refurbished two years ago. 

Blame is being heaped onto the private sector manager of the bridge.

Deputy Prime Minister and Interior Minister Matteo Salvini said the operator had earned “billions” from tolls but “did not spend the money they were supposed to” and its concession should be revoked.

Italian Prime Minister Giuseppe Conte said his government will not wait until prosecutors finish investigating the collapse to remove the concession from Autostrade, the main private company that maintains the country’s highways.

Conte, who led an emergency cabinet meeting in Genoa on Wednesday, called the tragedy “unacceptable in a modern society” and vowed to work so similar events will not happen again.

He said Italy will look for another company to maintain much of the nation’s highway system and will demand “more stringent” rules about maintenance.

“We cannot wait for justice” and that “all citizens must travel in safety,” he added.

Salvini said that those responsible would “pay, pay everything, and pay dearly”, as a criminal inquiry into the tragedy was announced.

Autostrade, a unit of Milan-listed Atlantia group, said it had carried out regular, sophisticated checks on the structure before the disaster and that these had provided reassuring results.

“Furthermore, the company’s technicians have relied, in order to assess the state of the viaduct and the efficacy of control systems being adopted, of companies and institutions which are world leaders in testing and inspections based on best international practices,” it said in a statement.

Conte called for the tonnes of debris which fell in Genoa to be removed swiftly, in order to facilitate rail travel and reduce the danger of floods.  He declared a 12-month state of emergency on Wednesday following requests from regional authorities.

The bridge links two highways, one leading to France and the other to Milan.

A wider evacuation order forced out about 630 people from nearby apartments following concerns about the stability of remaining large sections of the bridge.

Firefighters went inside some of the vacated apartments briefly to retrieve documents and, in at least one home, pet cats.

Building a new bridge could require demolishing the evacuated buildings, said transportation and infrastructure minister Danilo Toninelli.

Survivors of the Italian bridge collapse have described the moment the road fell away beneath them.

Davide Capello said he was driving across the bridge on Tuesday when “I heard a heavy sound, and I saw cars in front of me falling”.

He added: “I saw the road collapse then I fell with them. I thought it was all over for me.”

A French woman identified only as Leonine said she was travelling across the bridge with her husband and three-year-old son at the time of the collapse.

She said: “We saw the pylon go completely to the right, and we realised what was happening.”They tried to reverse the car, then “opened our doors, took our son out of his car seat and then left, running until the tunnel”.

In addition to the 39 confirmed dead, 16 people are injured, including nine in a serious condition. Three children were among those killed.

The dead included four French citizens travelling to a music festival and two Albanians.