Bank of Italy Governor Antonio Fazio was questioned on Monday by magistrates investigating a bank take-over scandal that has prompted calls for his resignation and tainted Italy's image.
Fazio's court appearance has taken the affair to a new level, putting it in the hands of the judiciary after Italy's politicians appeared to have lost interest because of their inability to oust him.
Communications Minister Mario Landolfi reiterated on Monday that it would have been better if Fazio had resigned and said he regretted that the case, which has poisoned the political debate, has ended up in court.
"Unfortunately I see there is a legal remnant to the affair which certainly doesn't help to improve the atmosphere," he said in a radio interview.
Fazio arrived at the Rome courts building just before 10 am (0800 GMT) and walked briskly into the offices of Chief Rome Prosecutor Giovanni Ferrara and Achille Toro, who is leading the bank probe.
After more than four hours of questioning magistrates called for a brief pause for coffee before the interrogation resumed.
One of Fazio's lawyers, Roberto Borgogno, told reporters Fazio had agreed to answer the prosecutor's questions and not to exercise his right to remain silent.
Fazio was placed under official investigation in August over accusations that he unfairly favoured Banca Popolare Italiana over Dutch competitor ABN Amro for control of domestic lender Antonveneta.
The Bank of Italy's chief inspector, Francesco Frasca, is also being investigated for abuse of office.
Being placed under investigation does not mean charges will necessarily be brought. There was no immediate comment from the Bank of Italy on Monday's questioning but it has previously reiterated it handled the take-over battle correctly.