Alex Salmond is facing calls to sack one of his special advisers after opposition leaders accused the aide of using "bully-boy tactics" and a "disgusting" personal attack on a mother-of-two.

Campbell Gunn, a senior special adviser and political spokesman for the First Minister, has apologised "unreservedly" to Clare Lally, who addressed a Better Together rally this week.

Ms Lally told pro-UK campaigners she was "just an ordinary mum from Clydebank".

She told how she was grateful for the care health workers had given her seven-year-old twin girls, one of whom has cerebral palsy, and wanted to "make sure our NHS remains the best in the world".

But Mr Gunn, in an email, is reported to have said that "the 'mother-of-two' who described herself as 'just a normal person' was a member of Labour's shadow cabinet and daughter-in-law of former Labour Lord Provost of Glasgow Pat Lally".

Ms Lally was appointed to Labour's shadow cabinet as a carers' champion, but is unrelated to the former Lord Provost.

She said: "Why is the First Minister's special adviser lying to the papers attacking me?"

Mr Gunn said he was "genuinely sorry" and that Mr Salmond had no knowledge of his email. He said: "Nothing in the email was intended to be a slight on Ms Lally or question her absolute right to express her views, and I apologise unreservedly for the upset and offence."

Labour leader Johann Lamont said: "Apologies are not enough. Alex Salmond must sack Campbell Gunn."