Giorgio Olivato, a vice chairman of a foundation that is the top shareholder in Italy's Banca Monte dei Paschi di Siena, has resigned barely three months after being named to the post. 

Monte Paschi is the oldest surviving bank in the world and the third-biggest bank in Italy.

Reasons for Olivato's resignation are yet to be disclosed. He is the second senior executive to resign from the foundation in less than a month. 

However, two sources knowledgeable on the matter said that Olivato staunchly opposed the foundation's plans to put up for sale a part or all of its 33.5% stake in Monte Paschi, Reutersol reported. 

The report said that the debt-ridden foundation is under fire to sell its shares quickly as the bank plans a EUR2.5 billion capital increase by the end of 2014. 

The sale will be a major move for the foundation, which until 2011 raked in big debts to keep its hold in the bank. It has gradually reduced its stake since then but it would lose its blocking minority should the foundation decide to cut its stake further, Reuters said. 

Early this year, Tuscan Monte Paschi secured a EUR4.1 billion government bailout to cover its cash shortfall.