Nicola Sturgeon has condemned the behaviour of her own MPs as “utterly unacceptable” after a leaked audio recording appeared to show some of the SNP’s Westminster group rallying behind a colleague who had been suspended for making an unwanted sexual advance to a teenage staff member. The party’s former Commons chief whip Patrick Grady was suspended from parliament for two days last week after an independent panel found he had behaved inappropriately towards the 19-year-old man at a social event in October 2016. At a bruising first minister’s questions (FMQs) session on Thursday, Sturgeon was repeatedly challenged over her party’s treatment of the victim. He has accused the SNP of serial failures in their handling of his informal then formal complaints, which have taken six years to reach a conclusion, during which time Grady was promoted and victim says he found himself ostracised by the Westminster office. Sturgeon offered to meet the man to apologise to him in person, amid widespread frustration among SNP activists with what many consider a systemic failure to deal openly and equally with harassment and other complaints. The Guardian understands that Sturgeon’s reprimand was met with “fury” from some SNP MPs, who believe they are being made to take responsibility for leadership failings both at Westminster and Holyrood. The group were reportedly threatened with criminal action over the leak to the Daily Mail of the recording, on which several MPs speak up for Grady, including Westminster leader Ian Blackford, who says he would “encourage the group to deliver as much support as possible”. Sturgeon’s criticism of the leaked recording, which she said “suggests that more concern was shown for the perpetrator of this behaviour than were shown for the victim of it”, will add force to repeated calls for Blackford’s resignation, although most had previously assumed his position to be safe because of his closeness to the first minister. On Tuesday evening, Blackford announced an external review after fellow MP Amy Callaghan accused the SNP of “clearly falling short” of supporting sexual harassment complainants. Grady’s victim immediately dismissed this as a publicity stunt. In broadcast interviews on Thursday evening, Blackford said he would not resign and that it was up to Grady “to reflect on his behaviour”. Meanwhile, in an indication of strength of feeling at the SNP grassroots, a group of respected activists is planning a motion to put to the next party conference calling for zero tolerance of sexual harassment and more explicit and consistent sanctions in dealing with complaints. Grady’s victim says that the way his complaint was handled – including him being moved from his job in the Whips office, rather than Grady himself being redeployed – has only compounded his stress, but that he has little faith in progress being made. He told the Guardian: “Any changes to party procedures would have to be passed at conference, which would mean victims and politicians would all have something to say and this is not a debate the party wants to have in public”. In her final report to the party’s national executive committee, published last December, the SNP’s former equalities convener Fiona Robertson warned of “years’ worth” of internal complaints still waiting to be handled by officials and a current system that is “not fit for purpose”. This criticism is reiterated by other SNP insiders, who say that the party has never dealt with becoming a mass membership organisation after 2014 and the consultation, transparency and accountability that demands. On Wednesday, the party’s youth wing posted an online statement calling for a review of the party’s complaints procedures at all levels, and urging on MPs and MSPs to “redouble their efforts to reinforce an atmosphere of tolerance, safety and inclusion in our party”. Another activist, who joined the party in 2019, after the referendum campaign, and is heavily involved in day to day campaigning, explained: “If we don’t improve the way we deal with harassment, I worry how it impacts on our vision for independence. We have new members coming in every day who feel left behind by the UK government, but how do we convince them the SNP isn’t just like the Tories? The party needs to take a long, hard look at itself”.