Dozens of people were wounded in Beirut on Saturday as security forces used tear gas and water cannons in clashes with protesters armed with tree branches and sign posts near Lebanon's parliament.
After a lull in largely peaceful protests which erupted in October, crowds spilled onto the streets again this week. They have been angered by a ruling elite that has steered the country towards its worst economic crisis in decades.
Police beatings and arrests in recent days have alarmed human rights groups and sparked fears among activists of a move to crush the dissent.
Witnesses said riot police fired rubber bullets and used water cannons in the commercial district on Saturday night. Smoke billowed out of tear gas canisters encircling protesters as ambulances sped through the streets of the capital.
President Michel Aoun ordered the country's army and security commanders to restore calm. Saad al-Hariri, who resigned as premier in October, said the clashes threatened civil peace. "It is an insane, suspicious and rejected scene," he tweeted.
The Internal Security Forces (ISF) said they were being "violently and directly" confronted and advised the public to leave the area. "Those who are rioting will be pursued, arrested and referred to the judiciary," it said on Twitter.
The Lebanese Red Cross said more than 60 people had been treated for injuries, with at least 40 others taken to hospital.
Young men chanting "revolution" hurled stones, steel barriers and flower pots at riot police, as protesters tried to enter the heavily barricaded part of central Beirut which includes the parliament.
Firefighters tackled a blaze which engulfed a protest camp in the centre of the city, where burning tents sent plumes of smoke into the air.
It was not immediately clear what caused the fire. The ISF denied local media reports that some of its forces had set the camp ablaze, where activists held debates and sit-ins in recent months.
Hundreds of people also marched and chanted against in the political class in other parts of the capital. A large banner at one of the rallies read: "If the people go hungry, they will eat their rulers."
Anger at the banks - which have curbed people's access to their savings - has also boiled over, with protesters smashing bank facades and ATMs on Tuesday night.
The unrest, which stemmed from anger at corruption and the rising cost of living, forced Hariri to resign in October. Feuding politicians have since failed to agree a new cabinet or rescue plan.
The Lebanese pound has lost nearly half its value, while dollar shortages have driven up prices and confidence in the banking system has collapsed.