A Nationals MP's claim that the Land and Environment Court's decision to block a coal mine in his electorate reflected an "ideological position" and "smacked of judicial activism" has prompted a rival MP to accuse him of contempt of court.

After the court on Friday rejected Gloucester Resources' bid to open the Rocky Hill mine on the Mid North Coast because of "climate change impacts", Nationals MP for the Upper Hunter Michael Johnsen hopped on 2GB to vent his fury.

Nationals MP for Upper Hunter Michael Johnsen. Credit:Max Mason-Hubers

The show's host Chris Kenny said: "Here you have a judge in a NSW land and environment court saying that he's protecting the planet from global warming, from climate change".

Mr Johnsen replied: "They are taking an ideological position, again it smacks of judicial activism, and it has nothing to do with the merits of the proposal itself and I’m very, very disappointed."