Prime Minister Malcolm Turnbull has for the first time offered explicit government support for a cut to penalty rates, saying he agreed with the decision announced this month.

Mr Turnbull had drawn criticism for repeatedly deflecting questions on his support for the Fair Work Commission's draft decision, which will see Sunday rates reduced from July.

Previously, Mr Turnbull had insisted it was not his government's decision, saying only he would respect the independent umpire.

But on Friday, a frustrated Mr Turnbull told radio 3AW interviewer Neil Mitchell that, "we do support it Neil".