UPDATE: The number of people killed in the explosion has risen to 100 and there are fears that it could reach up to 120 or even more.
The injured are more than 4000.
Greece is sending a Special Rescue Unit to aid the local forces.
A large blast has hit the Lebanese capital, Beirut, ahead of the verdict in a trial over the killing of ex-PM Rafik Hariri in 2005 killing at least 50 people, according to initial information, while reports from the Lebanon Red Cross say the dead could be in the hundreds. According to reports, there are 3,000 injured.
Reports say the explosion was in the port area of the city, with unconfirmed reports of a second blast. It is not clear what caused them.
Video posted online showed a large mushroom cloud and extensive damage.
A UN tribunal is due to issue its verdict in the trial of four suspects in the murder by car bomb of Hariri.
All four are members of the Iranian-backed Hezbollah group, which has consistently denied any role in Hariri’s death. They are being tried in absentia and the verdict is due on Friday.
The possible second explosion was reported to be at the Hariri residence in the city.
Lebanon’s health minister, Hamad Hasan, has spoken of many injuries and extensive damage.
Local media showed people trapped beneath rubble. A witness described the first explosion as deafening.
The latest reports come amid political tension in Lebanon, with street demonstrations against the government’s handling the worst economic crisis since the 1975-1990 civil war.