ROME — An Italian anarchist group claimed responsibility for a letter bomb that injured the national director of Italy’s tax collection agency after it exploded in his hands on Friday, the Italian police said.

The director, Marco Cuccagna, lost two fingers and sustained eye injuries on Friday after opening an envelope containing explosives, the police said.

A day earlier, the German authorities intercepted and defused a package bomb mailed to Josef Ackermann, the chief executive of Deutsche Bank, by the same group, the Informal Anarchist Front. The group also claimed responsibility for a series of letter bombs sent to foreign embassies in Rome a year ago that seriously injured two people.

Italy’s prime minister, Mario Monti, issued a statement of solidarity with Mr. Cuccagna and the tax agency, Equitalia, saying it had “always done its duty, in full respect of the law” and performed “an essential function” for the Italian state.