NSW Premier Gladys Berejiklian was advised by Treasury officials that negative gearing policies were pushing up house prices but declined to challenge her federal colleagues' support for it, leaked documents reveal.

A cabinet briefing reveals that top Treasury officials advised NSW to advocate a review of negative gearing tax concessions because they were pushing up house prices, but just weeks after that advice was given, the then new Premier declined to challenge the federal Coalition's support for the policy

Ms Berejiklian declared housing affordability her top priority upon becoming Premier last year and said she was "open minded" on the issue.

But she soon apparently shut down the possibility of picking a fight with Prime Minister Malcolm Turnbull over negative gearing policy despite just weeks earlier being being briefed by treasury officials that NSW should advocate the multi-billion dollar investor tax breaks be reviewed to supplement the "modest gains" being achieved by state government housing affordability policy.