Rome, January 18 - The centre-right coalition led by ex-Premier Silvio Berlusconi's People of Freedom (PdL) party closed the gap on the centre-left on Friday, less than six weeks before Italians were due to go to the polls to elect their new parliament. The centre-left coalition led by the Democratic Party (Pd) and its secretary Pier Luigi Bersani continued to top the weekly SWG opinion poll at 33%. However this was a 1.9% drop over the same day last week due to a fall in support for both the Pd and its main ally, Left Ecology Freedom (SEL) of Puglia Governor Nichi Vendola. The centre-right coalition came in at 27.2%, compared with 25.3% last week - a 1.9% gain. The rise in support was largely due to a 2% increase in the popularity of PdL, which offset a slight drop in support for its regionalist coalition partner Northern League. The centrist grouping led by outgoing technocrat Premier Mario Monti remained stable at 13.7%, just over three percentage points behind the populist and anti-establishment Five Star Movement (M5S) of Genoa comedian Beppe Grillo. After weeks of negative performance by the M5S a 0.9% rise in popularity took it to 16.8%.