'We don't know what it is at this stage', Luanda health official Vita Vemba told state radio, while announcing the setting up of a special commission comprising health, environment and local government officials.
The independent financial daily A Capital on Saturday blamed pollution in city's Cacuaco quarter for the rash of illnesses.
Two weeks ago, Cacuaco residents began complaining of a foul smelling 'green thick smoke' emanating from the chimney of a petroleum unit in the area, the director of the newspaper, Tandala Francisco, told AFP.
The factory has since been closed.
Symptoms including 'sleepiness, tiredness and difficulty with speech,' witnesses told A Capital. Authorities meanwhile refused comment.
Vemba however dispelled fears of a cholera or fever outbreak.
Oil-rich Angola's sole refinery is located in Cacuaco.