Security is tight in the Italian capital of Rome after mail packages exploded at a pair of embassies and as people prepare to celebrate Christmas.
Authorities are on high alert for additional strikes and continue to investigate Thursday's attacks on the Chilean and Swiss embassies, which officials say were carried out by a group named the Informal Anarchist Federation.
Two staffers – one at each embassy – suffered serious injuries when they opened manila envelopes about the size of a videocassette.
One man could lose vision in one eye, while the other could lose his badly-injured hand, officials said.
At least one of the devices contained an iron bolt that shot into the chest of one of the employees, Italian authorities said.
The twin blasts sent police scrambling to inspect other embassies for any threats.
The bombs were sent from within Italy, authorities said.
A day later, police have stepped up security in Rome as a precaution. Several large-scale events are scheduled Friday, including Midnight Mass at the Vatican. Thousands of people are expected to attend.
Mantovano told an Italian state radio station that security is being tightened at "possible targets," including embassies, detention centres for clandestine migrants, prisons and police stations.
Details emerged Friday about the anarchist group's alleged motive.
Alfredo Mantovano, Italy's interior ministry undersecretary, said the group wanted to avenge Chile and Switzerland's actions against the anarchist movement.
Mantovano said the Swiss embassy was targeted because Switzerland and Italy co-operated in the recent arrest of several anarchists.
He suggested Chile was attacked because "an anarchist who became a kind of myth for that world" was killed when a bomb he was carrying blew up in Santiago in 2009.
Italian media reported that a note found at one of the embassies cited the name of a Greek anarchist who was killed in a shootout with police last March.
The bombings have renewed concerns in Europe about terror attacks during the holiday season.
Last month, a wave of letter bombs was sent by a Greek anarchist group to several embassies in Athens. Three exploded or caught fire but no one was seriously injured.
With files from The Associated Press
