The Welsh Assembly’s standards commissioner Sir Roderick Evans has resigned, accusing an assembly member of secretly recording him.
Sir Roderick, who oversees complaints about AMs, said the unnamed politician recorded “highly confidential conversations with my staff”.
The retired high court judge alleged he had been recorded “over a period of what seems to be several months”.
He said the actions were “wholly unacceptable”.
Sir Roderick Evans has served as the assembly’s standards commissioner since 2017.
In a statement on Monday he said: “It has come to my attention that conversations with my staff about a variety of highly confidential and sensitive matters have been secretly, and possibly illegally, recorded over a period of what seems to be several months and in what seems to be a number of different locations by an assembly member.
“These have included highly confidential conversations with my staff including references to cases brought by members of the public.
“When considering and investigating complaints it is necessary for me and my staff to have open and frank discussions about the complaints, the appropriate approach to them, and their implications.
“That a member of our national assembly could behave in this way is wholly unacceptable. It undermines the integrity of the complaints procedure and brings our democratic process into disrepute. I’m not prepared to continue in my role as standards commissioner.
“I thank my staff for their support during the last three years, but I therefore ask you to accept my resignation.”
He was embroiled in a row last year after he said a video featuring a Labour AM’s face superimposed on a woman in a low-cut top was not sexist.
Earlier this year he was accused of double standards after he recommended a Plaid Cymru AM be reprimanded for a swear word in a tweet.