A homemade bomb exploded in front of the main tax collection office of a southern Italian town on Saturday, police said, the latest in a string of attacks against tax authorities in the country.

The overnight explosion in Lamezia Terme caused no injuries but shattered a window and damaged the entrance to the building, a police spokesman said. No claim of responsibility has been made.

Three explosive devices blew up outside the Naples offices of a state agency that collects overdue taxes and fines in January, and two letter bombs were sent to the same agency's offices in Rome in December.

One of the letter bombs was intercepted, but the other blew off part of a finger of the agency's director general.

An anarchist group said it had carried out the Rome attacks, and police in central Italy made more than 40 arrests last week for the attacks, including the letter bombs.