ROME, Dec 17 (Reuters) - The former director general of Italy's Treasury, Alessandro Rivera, is set to join investment firm Bain Capital as financial sector's senior adviser for the European market, a person with direct knowledge of the matter told Reuters on Sunday.

It was not immediately possible to reach Bain Capital for comment.

A key figure at the Italian Treasury first as head of the banking division and then as director general, Rivera was in the driving seat during major banking crises such as the rescue of two regional lenders by Intesa Sanpaolo and the state bailout of Monte dei Paschi di Siena in 2017.

Rivera left his post as director general in January after nationalist Prime Minister Giorgia Meloni replaced him with economist Riccardo Barbieri.

From January he will join a leading global private equity fund with $180 billion of assets under management.

Bain Capital is an investor in Italian companies such as payments giant Nexi, bad loan manager doValue and paper manufacturer Fedrigoni. (Reporting by Giuseppe Fonte; Editing by Valentina Za)