Labour's deputy leader Harriet Harman was today forced to apologise for branding a senior coalition minister a "ginger rodent".
Mrs Harman admitted she had been "wrong" to use the description about Liberal Democrat Chief Treasury Secretary Danny Alexander in a speech.
A statement issued by Labour said: "Harriet Harman has today apologised for her comment about Danny Alexander and says it was wrong."
The jibe was the most personal of a number aimed at political opponents in Mrs Harman's address to the Scottish Labour Party conference in Oban today.
"Many of us in the Labour Party are conservationists and we all love the red squirrel," she said.
"But there's one ginger rodent we never want to see in the highlands of Scotland - Danny Alexander."
Mrs Harman also dismissed another Lib Dem minister, Scottish Secretary Michael Moore as "the invisible man", and said she wanted to make the SNP's Scottish First Minister Alex Salmond and his deputy Nicola Sturgeon "endangered species".
The joke about Mr Alexander, the flame-haired MP for Inverness, Nairn, Badenoch and Strathspey, was greeted with laughter in the hall.
However, it quickly backfired as Mrs Harman found herself accused of insulting all Scotland's redheads.
George Lyon, Scottish Liberal Democrat election chair, said: "There is no depths to which the Labour Party will not stoop.
"They aren't fit to be in opposition, let alone in government."
The SNP also hit out at the Labour deputy leader over her "childish abuse" of Mr Alexander.
Nationalist MSP Shirley-Anne Somerville claimed the high proportion of redheads in Scotland meant Ms Harman's "silly remark isn't anti-Danny or anti-Lib Dem, it's anti-Scottish".
Ms Somerville, herself a redhead, added: "It's a gaffe that is overshadowing what Iain Gray thinks should be his big day."
She went on: "Coming from the doyenne of po-faced political correctness, these remarks show she and Labour have lost the plot since losing the election."