People in the Lebanese capital, Beirut, are to hold a minute of silence for the more than 200 people believed to have been killed by an explosion a week ago.
The commemoration will take at 18:09 (15:09 GMT), the exact time when 2,750 tonnes of ammonium nitrate stored unsafely at the port detonated.
The blast flattened nearby buildings and caused extensive damage elsewhere.
On Monday, the government resigned amid mounting anger at a ruling elite many accuse of corruption and negligence.
Prime Minister Hasan Diab’s announcement failed to pacify protesters, who clashed with police in central Beirut for a third consecutive night.
The demonstrations have been the biggest since last October, when an unprecedented economic crisis led people to demand a complete overhaul of the political system.
Before Tuesday’s explosion, almost half of Lebanon’s population were reportedly living below the poverty line and a third had lost their jobs.
Mr Diab, a university professor who took office in January with the support of the Iran-backed Hezbollah movement and its allies following the resignation of the previous government, blamed last week’s blast on the entrenched elite.
“Their corruption created this tragedy,” he said in a speech on Monday night. “Between us and change stands a thick wall protected by their dirty tactics.”
Mr Diab said that his caretaker administration would “follow the will of the people in their demand to hold accountable those responsible for the disaster”.
The BBC’s Tom Bateman in Beirut says it is unlikely the mass resignation of the government will remove much heat from the protests, as Lebanon’s problems are only deepening.
A new prime minister will have to be chosen using the same system of sectarian politics at the root of many people’s complaints, our correspondent adds.
More on the explosion in Beirut
Meanwhile, the recovery operation is continuing on the ground in Beirut.
The UN said on Tuesday that the World Food Programme would be sending 50,000 tonnes of wheat flour to Beirut to “stabilise the national supply and ensure there is no food shortage in the country”, with 17,500 tonnes arriving within two weeks.
The head of the agency, David Beasley, warned on Monday that he was very concerned that Lebanon could run out of bread in about two-and-a-half weeks because 85% of the country’s grain was usually delivered through Beirut’s port.
Mr Beasley said it was urgent to get the port up and running, and that he believed it could be temporarily operational in two to three weeks.
A port official noted that the container terminal suffered “minimal damage” and that on Monday night a ship docked there for the first time since the explosion.
At least 15 medical facilities, including three major hospitals, also sustained partial or heavy structural damage last Tuesday.
The UN has called for additional support to ensure those still functioning can continue to treat the estimated 6,000 people injured by the blast, and also manage the ongoing coronavirus pandemic.
On Sunday, a total of 294 new Covid-19 cases were recorded, a new record for Lebanon.
“The emergency in Beirut has caused many Covid-19 precautionary measures to be relaxed, raising the prospects of even higher transmission rates and a large caseload in the coming weeks,” the UN said.