Aberdeenshire West MSP Alexander Burnett has been reported to police amid allegations he broke election campaign spending rules.
A complaint has been made to Police Scotland in relation to Mr Burnett, who was elected in May of this year.
A spokeswoman for the force said the complaint, which is in relation to election expenses, was under consideration.
The SNP said the move “underlined the “seriousness” of the matter but the Scottish Conservatives dismissed it as “a politically-motivated fishing expedition”.
A spokesman for the SNP said: “The fact that these allegations have now been reported to Police Scotland, in line with the advice of the Electoral Commission, underlines the seriousness of this matter for Alexander Burnett and Ruth Davidson.
“As such, it is only right that the police are now given the opportunity to fully investigate any potential breach of election rules.”
A Scottish Conservative spokesman said: “The SNP tried the Electoral Commission first, was told it’d gone to the wrong place, and is now trying the police.
“It’s clear the nationalists are engaged in a nothing more than a politically-motivated fishing expedition.”