257 dead in Algerian military plane crash
Algeria's defence ministry was quoted as saying that 247 passengers and 10 crew members were among the dead following the crash.
The secretary-general conveyed his heartfelt condolences to the family of the victims and to the people and government of Algeria, said the statement.
More than 250 people were killed when an Algerian military plane carrying soldiers, their families and some refugees crashed soon after takeoff from a military base.
An Algerian military plane is seen after crashing near an airport outside the capital Algiers, Algeria on April 11, 2018.
Another deadliest plane crash in Algeria was back in 2003, when 102 people had lost their lives after a civilian airliner crashed at the end of the runway in Tamanrasset.
The Ilyushin IL-76 transport plane was bound for Tindouf in southwest Algeria near the borders with Morocco and Western Sahara.
The plane was heading to the city of Becan in the South-West of the country.
An Algerian ruling party official reportedly said also onboard were members of the Polisario Front, a separatist movement in West Sahara.
Algerian President Abdelaziz Bouteflika after the crash announced three days of national mourning, adding that prayers for the dead will be held on Friday, news agency AP reported. The plane came down in an open farm field near the base, the ministry says.
A local farmer described the moment he saw people leaping from the aircraft moments before the plane crashed at 7.50am local time on Wednesday. According to the Aviation Safety Network, the 2003 crash of an IL-76 of the Iranian Revolutionary Guard killed 275 people.
"The plane started to rise before falling", an unidentified man lying on what seemed to be a hospital bed told Ennahar TV.
In February that year, an Algerian Air Force Lockheed C-130 Hercules crashed in a mountainous area in eastern Algeria killing 77 passengers and leaving one survivor.
Earlier TV images showed flames and smoke billowing from the site of the crash, the country's worst air disaster. There was a single survivor in that crash.