SNP MP Mhairi Black is stepping down at the next general election, saying Westminster is “outdated, sexist and toxic”.

Ms Black, the party’s deputy leader at Westminster, became the youngest MP in more than 300 years when she was elected in 2015. Her decision to quit was described by former First Minister Nicola Sturgeon as the “loss of a unique talent”.

She becomes the sixth from her party to announce they will not contest the next general election.

The Paisley and Renfrewshire South MP also cited concerns over social media abuse and unsociable hours.

“I have also made clear that I have no desire to have a long career in elected politics, and as we approach the next general election, I will have been elected for almost a decade,” Ms Black said.

“I have dedicated a third of my life so far to Westminster – a truly unhealthy working environment.”

She added: “Since 2015, the lives of my loved ones have been turned upside down and inside out.

“Between media attention, social media abuse, threats, constant travel, and the murders of two MPs, my loved ones have been in a constant state of anxiety for my health and safety.”

Scottish Conservatives chairman Craig Hoy dismissed Ms Black’s reasons for leaving, claiming it was more likely a reflection of the disruption in the SNP.

“Mhairi Black’s decision to step down is yet another damning verdict from a senior SNP MP on the failing leadership of both Humza Yousaf and Stephen Flynn,” said Mr Hoy.

“As much as the Depute Leader tries to blame Westminster, in typical SNP fashion, the public won’t be fooled. Mhairi Black knows chaos is engulfing her party, which is why they are fighting like Nats in a sack.

“It speaks volumes about how bitter those feuds have become that Mhairi Black has thrown in the towel, just a few months after agreeing to become deputy leader, and decided not to fight another election despite not yet turning 30.

Ms Black, who married her partner Katie in June last year said she looked forward to continuing to campaign for an independent Scotland and for the SNP at the general election, “but I will do so as a campaigner rather than a candidate.”

Humza Yousaf, the SNP leader and Scotland’s first minister, described Ms Black as a “trailblazer” who was a “passionate supporter of independence, equality, social justice, and simply of trying to make life better for her constituents and the wider Scottish public”.

He added: “She has also served as a role model for young people, especially women, with an interest or a desire to get involved in politics.”

His predecessor Ms Sturgeon, who stood down earlier this year, said on Twitter: “I only hope it’s temporary. The world needs more Mhairi Blacks in politics, not fewer.”

Former SNP Westminster leader Ian Blackford is stepping down along with party colleagues Peter Grant, Angela Crawley, Douglas Chapman and Stewart Hosie.

The next general election is due to be held by January 2025, with the autumn of next year seen as the most likely date.