MILAN (Reuters) - Troubled Italian bank Monte dei Paschi di Siena (>> Banca Monte dei Paschi di Siena SpA) as expected on Wednesday appointed the head of Bank of America Merrill Lynch in Italy as its new chief executive.

Marco Morelli, who served as Monte dei Paschi chief financial officer before leaving the bank in 2010, returns to the Tuscan lender as it prepares to raise up to 5 billion euros ($5.6 billion) as part of an emergency rescue plan to avert the risk of being wound down.

Morelli replaces Fabrizio Viola, who agreed to step down last week under pressure from the Italian treasury and investment banks leading its capital raising consortium, according to sources close to the matter.

The bank said on Wednesday Chairman Massimo Tononi would also step down after a shareholder meeting due to be convened in coming weeks to approve the bank's rescue plan.

(Reporting by Silvia Aloisi; editing by Francesca Landini)