Rome, February 1 - Italy's centre left headed by Pier Luigi Bersani saw its lead narrow to just five points over Silvio Berlusconi's centre-right coalition, which has gained in popularity less than a month before elections, the latest SWG poll said Friday. The centre left had 32.8% of the projected vote after losing 1.3% compared to last week's poll by the independent group. Bersani, who heads the Democratic Party (PD), saw support for his coalition weaken after a derivatives scandal came to light at the Monte dei Paschi di Siena bank, which has historic ties to his party. Ex-premier Berlusconi, who is seeking his fourth term in office, saw support grow for the centre right by 1.2%, giving his coalition a projected 27.8% of the vote. The centrist coalition headed by outgoing Premier Mario Monti was up 1.4% with 14.2% of projected votes. The anti-establishment Five Star Movement (MS5) of comic Beppe Grillo stood at 18%, up 0.8% on the week. Civil Revolution, a new party led by Palermo anti-Mafia magistrate Antonio Ingroia, was down slightly to 5%, still above the 4% threshold needed in order to qualify for seats.