The Lebanese security forces on Saturday fired tear gas and rubber bullets at protesters in Beirut, some of whom tried to break into a barricaded central district of the capital.
The clashes continued into the early morning on Sunday as riot police used water cannon and more tear gas to disperse demonstrators who pelted them with stones.
Members of the security forces chased protesters in the streets, beating and detaining some of them, a Reuters witness and a protester said.
State news agency NNA said the tear gas made several people faint. Lebanese Civil Defence said it treated 54 injured people, taking more than half to hospital.
The Lebanese Red Cross told AFP that people were treated for breathing difficulties and fainting, along with injuries caused by stones. It said security personnel and civilians were among those treated.
The Internal Security Forces said at least 20 police officers were wounded.
Hundreds of people gathered as part of the wave of protests that has swept Lebanon since October 17, furious at a ruling elite that steered the country towards its worst economic crisis in decades.
Protesters accuse the political class of milking the state for their own benefit through networks of patronage.
Earlier on Saturday, dozens of young people opposed to the anti-government protest movement clashed with riot police in the capital, throwing rocks and firecrackers only to be met with volleys of teargas.
Young counter-protesters from an area of Beirut dominated by the powerful Shiite Hezbollah and Amal movements tried to raid an anti-government protest camp in Martyrs' Square on Saturday afternoon.
Riot police intervened, firing tear gas to disperse them.
The square, in central Beirut, has been at the centre of the protests over perceived official corruption, poor services and economic problems.
These large anti-government rallies, which grew into calls for an overhaul of the state, have mostly passed off peacefully.
However, clashes have become more frequent in recent weeks, with supporters of Hezbollah and Amal attacking protest camps in several cities.
Both Amal and Hezbollah are partners in Lebanon's cross-sectarian government.
The counter-protests have taken place in the capital and other Lebanese cities in recent weeks, prompting the leader of Hezbollah on Friday to urge his supporters and those of Amal to stay calm.
Hassan Nasrallah said that the "anger" of some of his movement's members had gotten "out of control" but claimed it had been quickly contained.
Lebanese security personnel had already used force to disperse anti-government protesters earlier this week.
Since the protests pushed Saad Hariri to resign as prime minister in late October, talks between the main parties about forming a new Cabinet have been deadlocked.
Lebanon urgently needs a new government to pull it out of the crisis which has also shaken confidence in its banking system. Foreign donors say they will help only after the country forms a Cabinet that can enact reforms.
