An Italian anarchist group with ties to the country's famed Red Brigade extremist organization claimed responsibility for two embassy bombings that left two people seriously injured and put the Italian capital on high alert.

The bombs arrived via post Friday to the Rome-based embassies of Switzerland and Chile, seriously injuring the hands, arms, and chest of both embassy clerks who opened the packages.

Police said the Swiss clerk might have to have one or both hands amputated, while the Chilean worker is at risk of losing sight in one eye.

A group called the Informal Anarchist Federation -- known by its Italian-language initials FAI -- Friday claimed responsibility for the blasts. Both of the packages included a message that read: "Long live FAI! Long live anarchy!"

The burned remains of a note found in the parcel at the Chilean embassy read: "We have decided to make our voice heard once again, with words and with deeds. We will destroy the system of domination."

The notes were signed by the FAI, but they claimed they were the work of a previously unknown FAI member group called the "Lambros Founas Cell." Lambros Founas was a Green anarchist killed in a shootout with police in March.

Italian Minister of the Interior Roberto Maroni said the attacks were likely related to Conspiracy of Cells of Fire, a group that carried out 14 similar attacks in Greece in November. Those attacks also included bombs sent to Italian Prime Minister Silvio Berlusconi, as well as to the leaders of France, Germany and Greece.

Italian authorities said the choice of the Swiss and Chilean embassies was likely linked to the arrests of anarchists in those countries, though the claim of responsibility from FAI made no mention of that.

Soon after the two explosions, police in Rome went on high alert, calling for x-rays of packages arriving to other embassies, while there was a visible police presence on the streets of the capital.

On Friday, the Pope gave his traditional Christmas Eve mass amid tightened security that Vatican authorities said was a response to the bombings the day before. In an apparent reference to the attacks, the 83-year-old pontiff used his homily to call on those listening to become "people of peace."

Police said Friday they believe the anarchists behind the two postal bombs were also responsible for helping turn protests in the wake of the Dec. 14 parliamentary confidence vote that allowed Berlusconi to narrowly hold on to power into violent clashes that sent dozens of people to the hospital and burned several cars and damaged shops.

It is the third time in less then a decade that FAI used the holiday season to launch a series of attacks.

In 2003, the group launched what it called "Operation Santa Claus," mailing hollowed out books full of explosives to four European Union government bodies, including one to Italian political leader Romano Prodi, who was then the president of the European Commission.

And a year ago, the group claimed responsibility for a bomb that went off just before Christmas in a pedestrian tunnel near Bocconi University in Milan.

According to the U.S.-based National Consortium for the Study of Terrorism and Responses to Terrorism and Italian intelligence documents between 2008 and 2009, the FAI is an umbrella group of small anarchist groups that has also claimed solidarity with the Red Brigades, the leftist guerilla group behind a long series of deadly attacks that ravaged Italy in the 1970s and 1980s and was responsible for the kidnapping and death of Italian Prime Minister Aldo Moro in 1978.