Labour's backing the Social Workers Registration Board and its call for compulsory registration of all social workers.

Currently registration is voluntary, a system the board says doesn't work.

Labour MP Carmel Sepuloni says the public has the assumption anyone calling themselves a social worker is qualified and has the necessary skills when that's not always the case.

"In the last ten years, and we've been looking into some of these, there has been a social worker in the limelight for something negative, and the vast majority of these were not actually registered social workers."

She's looking at drafting a Members' Bill on the matter to make sure social workers are compulsorily registered.