Police suspect the brothers are members of the New Red Brigades

The men are accused of being part of the New Red Brigades, the organisation that has claimed responsibility for the murder of two labour consultants.

The group is an offshoot of the Red Brigades, which sowed fear throughout Italy in the 70s and early 80s.

The two brothers, named by police as Maurizio and Fabio Viscido, are a postman and a postal clerk in Pisa.

Their arrests are the latest in a series of moves being co-ordinated by magistrates.

Palm-top diary

A shoot-out on a train last March led to the arrest of Nadia Desdemona Lioce, a leading suspect in the New Red Brigades.

Her palm-top diary has proved invaluable for the probe into the murders of two government consultants.

Last year, it led investigators to arrest nine suspected Red Brigades members, most of whom were not on the run but living apparently normal lives, and to the discovery of an arsenal in Rome.