Mr Fassino's spokesman has stressed that the transcripts offer no evidence of wrongdoing: the party leader was merely gathering information.

ECONOMIST: Italian politics

The conversation took place between the head of insurer Unipol and Piero Fassino, who was the leader of the biggest centre-left party and Mr Berlusconi's biggest political rival at the time.

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Piero Fassino has switched from foreign trade to the much trickier job of justice, while a former trade unionist, Ottaviano Del Turco, has moved from the parliamentary committee that deals with the Mafia to be finance minister.

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Quite apart from the potential damage it may do to the centre-left's election hopes, Mr Fassino's involvement with Unipol threatens further to dent Italy's reputation in the international business world, already battered by the Parmalat and Fazio affairs.

ECONOMIST: Italian politics