Lebanese authorities set up security perimeter in Beirut
Dozens of supporters of the two Shia-majority political movements tried to break into camps set up in Riad Al-Solh and Martyrs' squares, in which non-violent activists had gathered, and pelted them with stones.
Riot police charged at Amal activists and were driven back. In response, Hezbollah and Amal activists set alight tires and Molotov cocktails, which they launched in the direction of security forces.
Security and riot police subsequently increased their presence in the city and dispersed the movement's supporters using tear gas.
Activists say that Amal supporters had also gathered in large groups near the Ring Bridge in Beirut, with numbers increasing at night. Security forces have since closed off the bridge with iron gates.
Amnesty International has criticised the Lebanese authorities for failing to protect protestors from attacks from supporters of the Shia-majority movements.
Lyn Maalouf, Amnesty's Middle East research head, has called on authorities to act "immediately" to "uphold the right to peaceful assembly".
The latest developments emerge only a day after parliamentary police forces attacked peace protestors who marched outside the home Amal's head, Nabih Berri, casting doubt on their percieved neutrality.
Read more: Amnesty urges Lebanon authorities to protect protestors following increasing attacks
The clashes also took place on the same day as the UN International Support conference in Paris, to discuss conditions to ease the turmoil in Lebanon, which is facing a major economic and political crisis after months of protest.
Representatives from numerous financial and government institutions rejected caretaker Prime Minister Saad Hariri's request for a bailout, until the Lebanese government can offer guarantees of reform and change.