ADELAIDE, Feb 2 - Rankine says she wants to spend more time with her family and her decision to move to the back bench is not related to the controversy over recent child abuse cases within Families SA.

Premier Jay Weatherill says Rankine will be sadly missed at the cabinet table, describing her as "forthright, very passionate and one of the government's best communicators".

"I want to express my gratitude for her public service and wish her all the best on the next phase of her career where she will continue to serve the constituents of Wright," he said on Monday.

A replacement will be appointed in the coming days.

AAP