'There is a possibility of external interference through a rocket or bomb or other act'
Lebanon's president said on Friday its investigation into the biggest blast in Beirut's history would examine whether it was caused by a bomb or other external interference, as residents sought to rebuild shattered homes and lives.
Rescuers sifted rubble in a race to find anyone still alive after Tuesday's port explosion that killed 154 people, injured 5,000, smashed a swathe of the Mediterranean city and sent seismic shockwaves around the region.
"The cause has not been determined yet. There is a possibility of external interference through a rocket or bomb or other act," President Michel Aoun said in comments carried by local media and confirmed by his office.
Aoun, who had previously said explosive material was stored unsafely for years at the port, said the investigation would also weigh if the blast was due to negligence or an accident. Twenty people had been detained so far, he added.
One source said an initial probe blamed negligence.
While the United States has said it did not rule out an attack, Israel, which has fought several wars with Lebanon, has denied any role. Turkish President Tayyip Erdogan said the cause was unclear, but compared the blast to a huge 2005 bombing that assassinated former Prime Minister Rafik al-Hariri.
At Beirut's Mohammad Al-Amin mosque, next to Hariri's grave, chief cleric Amin Al Kurdi told worshippers in a Friday sermon that Lebanese leaders bore responsibility.
"Who is the criminal, who is the killer behind the Beirut explosion?" he said. "Only God can protect, not the corrupt ... The army only protects the leaders."
Security forces teargassed a crowd in Beirut on Thursday, as anger boiled over at the ruling elite, who have presided over an economic collapse.
The small crowd, some hurling stones, marked a return to the kind of protests that had become a feature of life in Beirut, as Lebanese watched their savings evaporate and currency disintegrate, while government decision-making floundered.
'Where is the state?'
"There is no way we can rebuild this house. Where is the state?" said Tony Abdou, an unemployed 60-year-old.
His family home is in Gemmayze, a district that lies a few hundred metres from the warehouses where 2,750 tonnes of highly explosive ammonium nitrate were stored for years near a densely populated area.
A security source and local media previously said the fire that caused the blast was ignited by warehouse welding work.
Some port officials have been ordered under house arrest.
Volunteers swept up debris from the streets of Beirut, which still bears scars from a 1975-1990 civil war.
"Do we actually have a government here?" said taxi driver Nassim Abiaad, 66, whose cab was crushed by building wreckage just as he was about to get into the vehicle.
"There is no way to make money anymore."
For many, the explosion was symptomatic of years of neglect by the authorities while corruption thrived.
"The problem is this government and all governments before it," said Dr. Mohammed Kalifa, 31, after Friday prayers.
Officials have said the blast, whose impact was recorded hundreds of miles (kilometres) away, might have caused losses amounting to $15 billion. That is a bill Lebanon cannot pay after already defaulting on a mountain of national debt - exceeding 150% of economic output - and with talks stalled on a lifeline from the International Monetary Fund.
Hospitals, many heavily damaged as shockwaves ripped out windows and pulled down ceilings, have been overwhelmed.
"I lived through part of the civil war. I saw people being shot in front of me. But never has there been such a horror," said Dr. Assem Al Hajj at Beirut’s Clemenceau hospital, which he said had treated 400 victims.