Former Lebanese officials on Wednesday called for the formation of an international investigation committee to investigate the blast in Beirut.
"Former Prime Ministers Najib Mikati, Fouad Siniora, Saad Hariri, and Tammam Salam find it necessary to ask the United Nations or the Arab League to form an international or Arab investigation committee composed of judges and investigators who are professional and impartial to start their duties in uncovering the circumstances and causes of the catastrophe that occurred in Lebanon," according to a joint statement released by Hariri's office.
The call was echoed by international aid and humanitarian organizations.
"Whatever may have caused the explosion, including the possibility of a large amount of ammonium nitrate stored unsafely, Amnesty International is calling for an international mechanism to be promptly set up to investigate how this happened," Amnesty International said in a statement.
Lebanon's President Michel Aoun stressed on Wednesday that the investigations would be transparent and will "hold those responsible accountable, and impose the harshest penalties on them."
Lebanese authorities declared Beirut a "disaster city" on Wednesday. They also declared a state of emergency in the city for two weeks.