Embattled One Nation senator Rod Culleton has been referred to Queensland police amid allegations he may have attempted to pervert the course of justice or even threatened a judicial officer.

Queensland Attorney-General Yvette D'Ath said on Tuesday she had asked police to investigate a letter allegedly sent by Senator Culleton to a Cairns magistrate asking for a matter before the court to be adjourned.

On November 15, Senator Culleton wrote to the Cairns Courthouse about a complaint from a person who was facing imprisonment in a Commonwealth matter. The letter foreshadowed a motion in the Senate to recall unnamed judges for "proven misbehaviour".

The letter noted Senator Culleton and others were watching with interest the conduct of all Australian judges after he claimed to have discovered an error relating to the status of the High Court.