Bomb found on underground train in Rome

It is thought the parcel bomb was found inside an empty carriage during a stop in Rebibbia, on the outskirts of the city.

The area has been cleared and bomb disposal experts are apparently defusing the device.

Reports have said it was left in a grocery bag underneath a seat, and was spotted by the conductor after passengers got off at the train's last stop this morning.

Officials said the bomb was composed of gunpowder and metal tubes and was hidden inside a shoe box.

There have been growing concerns in Europe about holiday season attacks following a suicide bombing in Sweden and official fears of an assault on a European city modelled on the deadly shooting spree in Mumbai, India.

On Monday, 12 men were arrested as part of terror raids in London, Stoke, Birmingham and Cardiff.

Rebibbia station was not evacuated and the metro system continued to function normally while investigations were carried out.

Security measures have been stepped up in Rome following violent anti-government protests last week and ahead of expected rallies on Wednesday.