ROME -- A suspicious package full of wires and powder was found Tuesday in a subway car in Rome, prompting a terror scare during the Christmas season. But the city's mayor said the device could not have exploded.

The device was found at around 10 a.m. inside a train at the Rebibbia station, on the outskirts of Italian capital. The train was at the end of the line and empty when the package was found, said Atac, which runs the Rome subway.

Bomb-disposal experts checked the powder and concluded "the device could not have exploded," Rome Mayor Gianni Alemanno was quoted as saying by the ANSA news agency.

It wasn't clear what type of powder was involved. Bomb disposal experts were analyzing it, Atac said.

Atac said in a statement the train was in an area beyond the platform that is used for maneuvering when the device was found.

Spokeswoman Diana Formaggio said the package contained powder and wires. She said the station was never closed and the service was not interrupted.

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

Rome has also been the site of violent anti-government protests in recent weeks during which demonstrators have set off flares, firecrackers and other devices; another such protest is planned for Wednesday.

Last year, a Libyan man set off a small bomb while trying to enter an army barracks in Milan, seriously injuring himself and slightly wounding the guard who stopped him. Officials said at the time that the man appeared to be opposed to Italy's military missions overseas: Italy has troops in Afghanistan.