(ANSA) - BELGRADE, AUG 19 - Violence erupted again late Monday evening in Belgrade on the sidelines of an anti-government demonstration organised by the protesting student movement. Following an apparent peaceful rally, several groups of demonstrators set up roadblocks throughout the capital's city centre before marching towards a branch of the conservative Serbian Progress Party (SNS), the ruling party led by President Aleksandar Vucic, which they pelted with rocks, bottles, firecrackers, and other items. Windows were shattered, garbage cans were overturned and set on fire, and protesters clashed with riot police who had arrived to protect the SNS headquarters. During the clashes, police responded to the throwing of stones and smoke bombs with stun grenades and tear gas, successfully pushing the protesters back. (ANSA).