Monte dei Paschi di Siena has a far bigger hole in its balance sheet than previously calculated, according to the European Central Bank, significantly raising the amount the Italian government has to deploy to rescue the troubled Italian lender.

The ECB told Monte dei Paschi that its capital shortfall was €8.8 billion ($9.19 billion), far higher than the €5 billion expected when the Italian government organised a rescue of the country's No. 3 lender last week. The higher amount reflects a serious decline in the bank's financial health during the months in which Monte dei Paschi and the Italian government have struggled to find a solution to its problems.