Corrective Services Minister Fran Logan has told parliament six staff at Acacia Prison have been sacked or resigned since 2015 after revelations of "inappropriate relationships with prisoners".

Last week WAtoday revealed two Acacia prison guards had resigned after it was alleged they had been in sexual relationships with inmates.

But today Mr Logan told parliament he had been informed of four other prison guards who lost their jobs over similar allegations.

Acacia Prison.

He said he ordered the Department of Justice to refer all six cases to the Corruption and Crime Commission.