(ANSA) - BELGRADE, APR 12 - Today marks a day of popular mobilisation and opposing demonstrations in Serbia. The central event of the three-day campaign in support of President Aleksandar Vucic and his government is scheduled for Belgrade, which began yesterday with thousands of people marching through the city centre and unfurling a 200-meter-long Serbian flag. In Novi Pazar, in the south of the country, the students in protest have called for their own new large protest against the authorities, accused of corruption, poor democracy and control over the media. In both cases, thousands of people are expected to attend, with supporters coming from all over. (ANSA).