Fresh clashes between Iraqi security forces and anti-government protesters broke out in Baghdad on Friday despite a call for calm by the countrys top Shiite cleric, Ali al-Sistani. Security forces fired tear gas and threw stun grenades into crowds of protesters wearing helmets and makeshift body armor on a main road in the middle of the Iraqi capital, sending demonstrators scattering, some wounded, Reuters reporters said. Sistani held security forces accountable for any violent escalation and urged the government to respond as quickly as possible to demonstrators demands. "The biggest responsibility is on the security forces," a representative of Sistani said in a sermon after Friday prayers in Kerbala. "They must avoid using excessive force with peaceful protesters." The demonstrators, mostly unemployed youths, demand an overhaul of the political system and a corrupt ruling class. More than 260 people have been killed since the protests began in Baghdad on Oct. 1 and quickly spread to southern provinces, according to police and medics. Police, the military and paramilitary groups have used live gunfire against mostly unarmed protesters since the beginning of the unrest. The violent response from authorities has fueled public anger. Snipers from Iran-backed militias that have participated in the crackdown were deployed last month, Reuters reported. Live fire is still being used and even tear gas canisters, fired directly at protesters bodies instead of being lobbed into crowds, have killed at least 16 people, New York-based Human Rights Watch said on Friday. Doctors at hospitals have shown Reuters scans of tear gas canisters embedded in the skulls of dead protesters. Sistani warned against the exploitation of the unrest by "internal and external" forces which he said sought to destabilize Iraq for their own goals. He said those in power must come up with a meaningful response to the demonstrations.