There were angry scenes in Siena as shareholders arrived for an assembly at the world's oldest bank. Italy's Monti dei Paschi was already seeking a 3.9bln euro bailout. But this week the Tuscan lender revealed a derivatives scandal could cost it a further 720 million euros. With elections just weeks away the case has become a political issue in Italy. The bank has links to the centre-left Democratic Party which is leading in the polls.