A Scottish MP who falsely accused a pro-Union campaigner of being a “holocaust denier” on Twitter has apologised and paid out £10,000 in damages to three charities, after a legal action launched against her was settled out of court.

Natalie McGarry, the MP for Glasgow East, said she had made a “serious mistake” and apologised “unreservedly” for comments she made about Alastair Cameron, the director of the campaign group Scotland in Union, on the social media site in March.

Ms McGarry was elected as an SNP MP at the general election in 2015, but withdrew from the party whip in November after the Women for Independence group called in police to investigate alleged financial discrepancies in its accounts.

The MP, who maintains she has done nothing wrong, was one of the group’s founding members.

On Monday she wrote on Twitter: “On March 6 I tweeted that the Scotland in Union was headed by an ‘internet troll’ and an ‘outed holocaust denier’. I made a serious mistake and accept there is no truth to those statements and apologise unreservedly to Mr Cameron for any distress caused.”

Mr Cameron said a share of the payout would be given to the veterans’ mental health charity Combat Stress, the Aegis Trust, which works to prevent genocide and crimes against humanity, and children’s charity Lumos, following the deduction of legal costs.

‘Strong opinion’

“I am pleased to accept this apology from Ms McGarry and draw a line under this unfortunate incident. I am delighted that some good will now come of this,” he added.

“Politics in Scotland invokes passion and strong opinion on all sides, particularly on social media. I hope this serves as a reminder to us all that we need decency and respect in our debate, whether we agree with people or not. I look forward to continue making the positive case for Scotland in the UK.”