As Rome's bus company ATAC prepares to increase its ticket prices on 25 May, a protest group has called for a demonstration at 13.00 that day outside the ATAC headquarters on Via Prenestina 45.

Calling itself the Comitato Romano per le Autoriduzioni, the group made the protest call from its "Non vi paghiamo" blog. In recent days stickers containing diagrams on how to bypass Rome's metro turnstiles have started to appear on the walls of the capital's schools and metro stations.

It is part of a wave of material against the price increases currently in circulation, including mobile phone apps which allow commuters to report the whereabouts of ticket inspectors via Twitter, and the online publication of the "Fake Atac" software that shows how to forge ATAC student passes.

The new 100-minute ticket, valid on the city's buses, trams and metro, will increase from