A worker who was trapped for 10 hours in a collapsed mediaeval tower in Rome has died after he was rescued.

The Romanian man was working on the restoration of the 13th century Torre dei Conti, in the Roman Forum, when the accident happened.

The 29-metre tower near the Colosseum appeared to have crashed to the ground twice, videos posted on social media and Reuters video showed.

Another worker, also Romanian, was pulled out almost immediately and hospitalised with serious but not life-threatening head injuries. Two more workers suffered minor injuries and declined hospital treatment.

Hundreds of tourists gathered in one of the busiest tourist sites in Rome to watch as firefighters tried to rescue the trapped man, named as Octay Stroici.

They used a mobile ladder to bring a stretcher to the upper level of the tower during the first rescue attempt.

Suddenly, another part of the structure partially collapsed, sending up a cloud of debris and forcing firefighters to scramble to safety.

The first collapse struck the central buttress of the structure’s southern side and caused the partial collapse of an underlying sloped base.

The second collapse hit part of the stairwell and roof, cultural heritage officials said in a statement.

The man was pulled out of the rubble alive over 10 hours after the collapse.

However, he went into cardiac arrest and could not be revived when he reached the hospital, Italian media reported.

“I express deep sorrow and condolences, on behalf of myself and the government, for the tragic loss of Octay Stroici, the worker who was killed in the collapse of the Torre dei Conti in Rome,” Italy’s Prime Minister Giorgia Meloni said.

“​We are close to his family and colleagues at this time of unspeakable suffering.”

None of the firefighters were injured.

Rescuers faced a complex task as the structure continued to give way as they tried to get near the trapped worker through a first-floor window, forcing their retreat on telescopic aerial ladders in a cloud of smoke.

Another approach on two ladders was also aborted and a drone sent up in their stead.

As dusk approached, firefighters lifted on a crane used giant tubes to suck rubble out of the second-floor window.

They continued the work into the night.

Authorities have seized the construction site, Italian daily Corriere della Sera reported.

The tower, which was due to be converted into a museum and conference space, is halfway along the Via dei Fori Imperiali, the broad avenue that leads from central Piazza Venezia to the Colosseum.

The building was still standing, but with significant internal damage.

It once hosted city hall offices but has not been in use since 2006 and was being worked on as part of a four-year renovation project due to end next year, according to Rome city authorities.

The tower’s restoration includes conservations work, the installation of electrical, lighting and water systems and a new museum installation dedicated to the most recent phases of the Roman Imperial Forum, officials said.

Before the latest phase was started in June, structural surveys and load tests were carried out “to verify the stability of the structure, which confirmed the safety conditions necessary” to proceed with work, including asbestos removal, officials said.

The current work, carried out at a cost of €400,000 ($A700,000), was just about complete.

Due to the EU-funded restoration work, the area around the tower was closed to pedestrians.

The building was erected by Pope Innocent III for his family in the early 13th century, and was originally twice as high. It was scaled down after damage from earthquakes in the 14th and 17th centuries.

Before the latest renovation phase was started in June, structural surveys and load tests were carried out “to verify the stability of the structure, which confirmed the safety conditions necessary” to proceed with work, including asbestos removal, officials said.

Italian prosecutors arrived at the scene as the rescue operation was underway and were investigating for possible charges against negligent disaster and negligent injuries, Italian media reported.

It is common in Italy for investigations to begin while an event is ongoing and before possible suspects are identified.

Rome Mayor Roberto Gualtieri and Italian Culture Minister Alessandro Giuli were at the scene.

“The firefighters risked their lives with the second collapse. We are worried for the worker who remains trapped,” said Federico Mollicone, chairman of the parliamentary culture committee.

–with AP and DPA