The correct spelling is BANDIERA ROSSA (RED FLAG). I can't remember if the exact title is AVANTI POPOLO (Go ahead, people!) or Bandiera Rossa, but Teru could be right. I can remember the tune and the first lines of the lyrics - Teru is right again, they are quite simple and repetitive.
I give a rough english translation (at my best...)

Avanti popolo (People, ahead!)
Alla riscossa (To the counter-attack)
Bandiera rossa (Red flag)
Bandiera rossa (Red flag)

Avanti popolo (People, ahead!)
Alla riscossa (To the counter-attack)
Bandiera rossa trionfera' (The red flag will triumph)

Ciao
Ezio