UN human rights experts and Amnesty warned Tuesday that Lebanese authorities were failing to protect protesters, following attacks on demonstrators by government supporters.
The authorities have "failed to adequately protect protesters from violent attacks by others", said a statement signed by a group of independent rights experts affiliated with the United Nations.
Signatories included Agnes Callamard, special rapporteur on extrajudicial, summary or arbitrary executions, and Michel Forst, special rapporteur on human rights defenders.
"Security forces have reportedly failed to intervene to protect peaceful protesters or arrest perpetrators on at least six occasions," they said.
London-based rights watchdog Amnesty International warned that attacks on protesters could signal a "dangerous escalation".
"The authorities must act immediately to protect protesters and uphold the right to peaceful assembly," said Lynn Maalouf, Amnesty´s Middle East research head.
Street protests demanding an overhaul of Lebanon's entire political system have rocked the small Mediterranean country since mid-October.
As its bitterly divided political leaders struggle to form a new cabinet, supporters of political factions have targeted demonstrators.
On Sunday night, supporters of Lebanon's two main Shiite parties -- Hezbollah and Amal -- briefly attacked protesters blocking a key Beirut flyover, in the most serious such confrontation since the start of protests.
The following night, dozens of youths again taunted anti-government activists in central Beirut and the southern port city of Tyre.
On Tuesday, supporters of the Free Patriotic Movement -- a party founded by President Michel Aoun -- confronted dozens of protesters who were calling on the head of state to schedule parliamentary consultations.