ministerial

Conservative MP Alicia Kearns, who previously employed Mr Cash as a parliamentary researcher, said it was "inexplicable" that the trial would have collapsed "without either ministerial or national security advisor or executive involvement".

Fracking is currently only limited by a suspension on ministerial decisions to grant licences.

Ross asked for a formal investigation on whether Hepburn breached the ministerial code, saying his behaviour had fallen "well below the standards" for ministers.

Ross has now written to John Swinney asking for a formal investigation about whether Hepburn breached the ministerial code, saying the behaviour "falls well below the standards set out" for ministers.

Johnstone added that ministers also have to adhere to the Scottish ministerial code.