Conservative Assembly Member Nick Ramsay has been arrested and suspended from the party.
ITV Cymru Wales understands the 44-year-old was arrested at his home on Wednesday night.
The Conservative Party was informed on Thursday morning.
The former driving instructor was elected as an AM for Monmouthshire in 2007 and has previously stood to be leader of the Conservatives in the Assembly.
He is currently the Shadow Finance Minister and chairs the influential Public Accounts Committee.
A statement is expected later about his membership to the Conservative Party.