Part of a medieval tower in the heart of Rome's tourist district has collapsed, trapping one man and leaving another critically injured.

A section of the Torre dei Conti, on the edge of the famous Roman Forum and close to the Colosseum, gave way just after 11:30 local time (10:30 GMT).

It's a very complex situation for the firefighters because there is a person trapped inside, Rome Prefect Lamberto Giannini said. The man is conscious and communicating with rescue workers.

The tower has been closed to the public for many years and was undergoing conservation work when a section collapsed.

While rescue efforts were still under way, a second section of the 29m (90ft) high tower began crumbling again, with bricks raining down, creating a huge cloud of dust.

The firefighters were unharmed, pausing their rescue work for a time, but then continuing their search for the missing man.

After the initial collapse, firefighters put up some protection around the trapped man, so when the second collapse happened, they obviously shielded him, Lamberto Giannini said.

It will be a very long operation because we have to try to save the person, but we also have to try to mitigate... the enormous risks faced by the people trying to carry out the rescue, he added.

A police chief has stated there is no imminent danger that the tower will disintegrate.

One worker was taken to hospital in a critical condition, local and foreign news agencies report.

Another worker, 67-year-old Ottaviano, who was inside at the time of the collapse but escaped from a balcony uninjured, told AFP news agency: It was not safe. I just want to go home.

Rome's mayor and the country's culture minister have visited the scene. A crane and drone are also being used to assist with the rescue operation.

The 13th Century tower is part of the Roman Forum, a major tourist attraction right in the heart of the city, but it is separated from the main visitors' area by a road. The streets all around have been taped off by police as a precaution.

The medieval tower was built by Pope Innocent III as a residence for his brother.

}