Julie Dettbarn, who represents Kyle on South Ayrshire Council, reportedly used the “n-word” in group chat with colleagues.
Dettbarn, 56, told the Ayrshire Post: “During a group chat with SNP colleagues, I used an outdated phrase that I recognise as being entirely unacceptable. I apologised to colleagues for the offensive nature of that phrase at the time.
“It was a lazy and stupid comment and there is no excuse for that.”
She added: “People in South Ayrshire expect better than that from those holding elected office.”
Dettbarn is also stepping down from her role as the local authority’s chair of health and social work.
In a statement, the SNP said: “Councillor Dettbarn has taken full responsibility for her unacceptable language and quit her council role. She’s currently suspended pending disciplinary action.”