Scientists make surprise discovery about volcano in Rome's Alban Hills.

Italian scientists have warned that a long-dormant volcanic complex in Colli Albani, a set of hills about 20km southeast of Rome, is actually still active and "waking up."

Experts at the National Institute of Geology and Volcanology in Rome say the volcano has the potential to erupt as violently as Mount Vesuvius did in 79 AD, when it destroyed nearby Pompeii.

However the good news is that the volcano in the Alban Hills on the outskirts of Rome is not expected to erupt for about another 1,000 years.

The surprise discovery of tectonic movement was made during research into historic eruption patterns of the Colli Albani volcanic complex, which last erupted 36,000 years ago.

Scientists also discovered that the ongoing pressure of gas and magma underground is causing the hills to rise by 2 millimetres each year.