Monte dei Paschi di Siena , Italy's third biggest lender, will approve a restructuring plan on Tuesday that could force its nationalization unless it can find private investors willing to bet on a bank hit by scandal and bad debts.

Following are a few facts about the bank:

- Founded in 1472 as a pawnshop to help the poor, the bank says it is the world's oldest lender still operating. Its main shareholder is a foundation with close ties to local center-left politicians in the medieval city of Siena and the surrounding Tuscany region.

- The bank has been hit hard by the euro zone debt crisis because of its large, 29-billion euro Italian government bond portfolio. In February, it received a 4.1 billion euros state bailout, which needs to be approved by the European Commission.

- In May 2012 prosecutors launched a probe into Monte dei Paschi's 2007 acquisition of smaller rival Antonveneta from Spain's Santander for 9 billion euros, which badly stretched the Siena bank's finances. They allege that the bank's former management misled regulators over a hybrid financial instrument it used to partly fund the acquisition.

- The probe was widened in January after the bank revealed the existence of three loss-making derivative contracts its previous management had made between 2006 and 2009. Prosecutors say the trades were used to conceal losses at the bank and their true nature was hidden from regulators.

- Monte dei Paschi posted total net losses of nearly 8 billion euros in 2011 and 2012. Under a previous restructuring plan drafted by CEO Fabrizio Viola and Chairman Alessandro Profumo - who were appointed in 2012 to turn the bank's around - it is shedding 4,600 jobs and cutting 400 branches, or 13 percent of its network. The EU wants the bank to cut costs further, reduce its exposure to government bonds and increase capital by 2.5 billion euros in 2014 - more than twice the amount originally planned by the bank.

(Reporting by Silvia Aloisi; Editing by Giles Elgood)