After the explosion, Interior Minister Nouredine Yazid Zerhouni said the blast was 'apparently accidental', and added that an inquiry would 'determine the exact causes'.

State power company Sonelgaz, which owns and operates the Hamma station, said: 'The cause of the blast has not been determined'. Government-controlled media blamed the explosion on 'a technical incident'.

Newspapers cited anonymous witnesses and observations, such as a large crater in front of the power station and the perimeter wall's collapse 'toward the inside', as potential evidence of an attack.

The station, inaugurated by President Abdelaziz Bouteflika in 2002, supplies electrical installations throughout the country.