Siena, February 4 - Giuseppe Mussari, the embattled ex-chairman of the Banca Monte dei Paschi di Siena (MPS) bank, met prosecutors in Siena on Monday, but did not answer their questions, his defense lawyer Fabio Pisillo said. Pisillo said Mussari would speak, but not without the additional presence of his other defense attorney, who was busy with another case on Monday. Prosecutors called Mussari to question him about alleged fraud at MPS, which was thrown into crisis in January when it emerged that a shady series of derivative and structured finance deals produced losses of 720 million euros. There have also been reports of bribes and corruption by bank officials regarding, among other things, the nine-billion-euro acquisition of rival Antonveneta in 2008. In questioning with police in Rome, Antonio Rizzo, a former manager for Dresdner Bank, on Monday reiterated his allegation there was a ''5% gang'' of MPS managers at the time of the Antonveneta takeover who took an kickback on every bank operation. Mussari became chairman of the banking association ABI after he left MPS, but resigned from the post after news of the derivatives scandal broke in January.