At least 728 people have been wounded in clashes with authorities as thousands of protesters hit the streets of central Beirut as riot police fire tear gas at those trying to break through a barrier to the parliament building. One police officer was also reported killed.
Lebanon's Prime Minister Hassan Diab has called for early polls after Tuesday's deadly blast, saying it is the only way out of the country's crisis.
Lebanese authorities have taken into custody 19 people as part of an investigation.
At least 158 people were killed in the explosion and more than 6,000 others injured, but numbers are expected to rise as search and rescue operations continue for missing people.
Beirut port blast crater 43 metres deep, says security official
The huge ammonium nitrate explosion in Beirut's port that devastated much of the city left a crater 43 metres (141 feet) deep, a security official.
"The explosion in the port left a crater 43 meters deep" Tuesday, the official told AFP, citing reports by French experts conducting an assessment of the disaster area.