The device was found in an empty train carriage in the Italian capital, but could not have exploded as a detonator was missing, according to authorities.
Parcel bomb found aboard Rome metro car
ROME // A homemade parcel bomb was found hidden inside a shoe box on an empty train carriage in Rome's metro system on Tuesday, officials said, amid heightened tensions over student protests in the city.
The device was composed of two short metal tubes stuffed with gunpowder that were connected by wires and had an antenna, but the detonator was missing.
It was found by a metro transport worker at around 10:00 am (0900 GMT) in a service area near Rebibbia station on the northeast outskirts of the city.
"The detonator was missing. It was made up of two tubes connected by wires with an antenna," Salvatore Cagnazzo, head of operational command in Rome for the Carabinieri paramilitary police force, told AFP.
Security measures have been stepped up around the Italian capital following a violent protest against Prime Minister Silvio Berlusconi last week and ahead of major student rallies expected on Wednesday.
Prosecutors have opened an inquiry on possible charges of possession and handling of explosive material and police officers were analysing CCTV footage to try and see how the bomb was brought onto the train.
The train started out from Laurentina station in southwest Rome, passing through the city centre and ending up at Rebibbia in northeast Rome.
The device could not have exploded," said Giampaolo Polizzaro, a spokesman for Rome city council, adding that it was inside a blue box in a plastic bag.
The website of the Corriere della Sera newspaper quoted a police source saying it could have been a pipe bomb -- a popular type of improvised device.
Rome mayor Gianni Alemanno said the news was "worrying" and he congratulated the security forces for their quick reaction to the alert.
Alemanno said security officers have now checked all the stations on Rome's metro system and found no other type of suspect packages.
Renata Polverini, head of the Lazio region around Rome, warned against a return to the violent militancy seen in Italy during the 1970s.
"Let's stop in time because we remember those years as dark years for which we are still paying a high price," Polverini said.
The bomb was found under a seat after the last passengers had descended, Rome's transport authority ATAC said in a statement.
Officers were called "immediately" and isolated the area where the bomb was found but the station was not evacuated, ATAC said.
The metro system continued functioning as normal during the operation.