Tear gas has been fired in Beirut as people protesting against the government's handling of this week's explosion tried to reach the parliament building.
Riot police took action as about 5,000 people gathered in the central Martyrs' Square and attempted to break through a barrier.
"The people want the fall of the regime," protesters chanted, adding: "Leave, you are all killers."
Makeshift gallows and nooses have been set up.
Sky News correspondent Alex Rossi, who is there, said residents have been "enormously angry" since the explosion happened, adding: "People here want to - metaphorically at least - hang their political class."
He said there was a "huge amount of structural damage to the buildings" and hardly any windows have glass in them.
Student Celine Dibo, speaking as she scrubbed blood off the walls of her shattered apartment building, said there was "no trust" in the government, adding: "I wish the United Nations would take over Lebanon."
Psychologist Maryse Hayek said the Lebanese people are "living in ground zero".
"I hope another country would just take us over. Our leaders are a bunch of corrupt people," he said.
One of the demonstrators in Martyrs' Square, Rose Sirour, said: "We want a future with dignity - we don't want the blood of the victims of the explosion wasted."
The number of dead has risen to 158, the Lebanese health ministry said. At least 6,000 have been injured, while 21 people remain missing.
The Kataeb Party, a Christian group that opposes the current Hezbollah-backed government, said on Saturday that its three members of parliament were standing down.
"I invite all honourable (members) to resign so that the people can decide who will govern them, without anybody imposing anything on them," said leader Samy Gemayel.
Earlier, Lebanon's president revealed he knew about the huge stockpile of explosives at Beirut's port almost three weeks before they blew up.
The ammonium nitrate had been there since 2013 after being confiscated from an impounded cargo ship.
Michel Aoun was told about the 2,750 tonnes of material on 20 July, and claims he subsequently ordered officials to "do what is needed".
But he said he had "no authority to deal directly with the port" and did not know "where it was placed".
Documents show Lebanese authorities in customs, the military, security and the judiciary raised the alarm 10 times in the seven years the explosives were there.