Pannella, who has long crusaded for the legalisation of so-called soft drugs, presided over the handout of some 450 bags, each containing a half- gram, or about one-fiftieth of an ounce.
Asked where he got the hashish, Pannella replied: "We got it from the market. We took it away from the Mafia."
Two Pannella supporters turned themselves in to police to publicise the campaign. They were an Italian aide, Rita Bernadini, and a Belgian member of the European Parliament, Olivier Dupuis, promoters said. Mr Bernadini was back out in Piazza Navona in the afternoon for another round of distribution. During the morning giveaway, police confiscated some of the bags.