Come clean on preference deal: Abbott

Prime Minister Julia Gillard says no policy promises have been made to secure Greens' preferences in the lower house, in exchange for Labor's upper house preferences.

But Mr Abbot's told the Seven Network, preferences don't come for free.

He says the deal will mean a higher mining tax and a carbon tax sought by the Greens, if Labor wins the August 21 election, and that'll mean higher electricity prices.