French President Emmanuel Macron has called for urgent support for Lebanon after flying in two days after a devastating blast ripped through Beirut, killing 145 people and generating a seismic shock that was felt across the region.
Dozens are still missing after Tuesday's blast at the port that injured 5000 people and left up to a quarter of a million without homes fit to live in, hammering a nation already reeling from economic meltdown and a surge in coronavirus cases.
A security source said the death toll had reached 145, and officials said the figure was likely to rise.
Macron, making the first visit by a foreign leader since the explosion, promised to help organise international aid for Lebanon but said its government must implement economic reforms and crack down on corruption.
"If these reforms are not made, Lebanon will continue to suffer," Macron said after being met by his Lebanese counterpart Michel Aoun at Beirut airport.
At the port, destroyed by Tuesday's giant mushroom cloud and fireball, families gathered seeking news about the missing, amid public anger at the authorities for allowing highly explosive ammonium nitrate to be stored there for years in unsafe conditions.
"They will scapegoat somebody to defer responsibility," said Rabee Azar, a 33-year-old construction worker, speaking near the smashed remains of the port's grain silo.
Prime Minister Hassan Diab declared three days of mourning from Thursday.
With banks in crisis, a collapsing currency and one of the world's biggest debt burdens, Economy Minister Raoul Nehme said Lebanon had "very limited" resources to deal with the disaster, which by some estimates may have cost the nation up to $US15 billion. He said the country needed foreign aid.
Offers of medical and other immediate aid have poured in, as officials have said hospitals, some heavily damaged in the blast, do not have enough beds and equipment.
The government's failure to tackle a runaway budget, mounting debt and endemic corruption has prompted Western donors to demand reform.
Lebanon's president blamed the explosion on 2750 tonnes of ammonium nitrate, used in fertilisers and bombs, that had been stored for six years at the port after it was seized. He promised to investigate and hold those responsible to account.
The government ordered some port officials to be put under house arrest.
But ordinary Lebanese, who have lost jobs and watched savings evaporate in the financial crisis, blamed politicians in charge during decades of state corruption and bad governance.
"Our leaders are crooks and liars. I don't believe any investigation they will do. They destroyed the country and they're still lying to the people. Who are they kidding?" said Jean Abi Hanna, 80, a retired port worker whose home was damaged and daughter and granddaughter injured in the blast.
An official source familiar with preliminary investigations blamed the incident on "inaction and negligence", saying "nothing was done" to remove hazardous material.
A Lebanese security source said the initial blaze that sparked the explosion was caused by welding work.
Veteran politician Walid Jumblatt, leader of Lebanon's Druze community, called for an international investigation, saying he had "no trust" in the government to find out the truth.
The White House said the US government had still not ruled out the possibility that Tuesday's explosion was an attack.
The World Bank said it would work with Lebanon's partners to mobilise financing for reconstruction.