South Sudan’s former vice president has told Al Jazeera that he will challenge his old boss for the nation’s top job.

President Salva Kiir sacked his deputy Riek Machar and the entire cabinet last Tuesday, in a move that his spokesman said was aimed at reshuffling and reducing the size of the government.

Machar called it is a step towards dictatorship.

He spoke exclusively to Al Jazeera’s Peter Greste in Juba.