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.