AN investigation has been launched after a union’s Twitter account shared an “unauthorised” anti-trans tweet prompting outrage.

On Sunday, Unison Scotland’s Twitter account, which has more than 10,000 followers, retweeted a post from an anonymous anti-trans account named Males In Disguise.

The account had shared a screenshot from a Reddit post discussing Mother's Day as a transgender woman.

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The Males in Disguise account frequently shares anti-trans memes and posts, relating to the use of bathrooms and single-sex spaces.

The Unison Scotland account had also retweeted a post from Helen Joyce, a gender-critical feminist and director of the Sex Matters group, which campaigns on transgender people’s participation in sport.

In a statement released on Monday, the union said that they “deeply regret” the offence caused by the social media activity, and insisted it did not represent the views of Unison.

The screenshot, taken from Reddit, reads: “Today I was told I’m not a mother. My wife told me you won’t steal this day from me and it really hurt, so to all trans woman out or not, who have kids, adopted or not, happy Mother’s Day. This day is for all of us even if we can’t celebrate the way we want. Try and treat yourself and enjoy today as the real woman that you are.”

The Males In Disguise account added: “Only on the internet can a man try to make Mother’s Day about himself”.

After freelance journalist James McEnaney shared the posts and asked for an explanation, the Union replied: “It was a genuine mistake. Sorry. We have undone retweet. Again sorry.”

Many other social media users criticised the union for the incident.

One wrote: “So the official Unison Scotland account (they represent 150,000+ members) retweeted and liked a bunch of overtly transphobic accounts/content and then when people noticed and called it out they're like "oops my bad uwu".”

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Another, noting the apology, added: “This was how @unisonscot replied yesterday, and I think this isn't good enough, given that this incident has understandably shaken trans member's faith in Unison Scotland.

“There should be an official statement in this, and measures put in place to ensure it never happens again.”

One added: “No way do the anti-trans tweets just happen across Unison Scotland's timeline and accidentally get retweeted.

“The 'accident' here is clearly someone retweeting thinking they were on their personal account. So who on Unison's social media team holds these views?”

While another added: “Absolute bollocks. Unison Scotland was retweeting several horrendous transphobic accounts including Helen Joyce.

“It wasn't "a mistake" it was at least one member of staff retweeting hate speech and saying "oo sorry it was a mistake" is institutional cover for transphobia.”

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On Monday, Unison released a statement, which said: “On Sunday, an unauthorised tweet came from Unison Scotland’s account.

“Unison deeply regrets the offence caused by this unauthorised social media activity. This in no way represents the views of Unison and is against Unison’s policy.

“The comments were removed as soon as we were made aware and we are now conducting an internal investigation.

“Unison is unequivocal in our support of transgender people's rights and will continue to fight for equality for all.”