Sinéad O’Connor has announced she is joining Sinn Féin and has called on Gerry Adams and other veteran republicans to step down from the party’s leadership.

Adams has faced severe criticism over his handling of two sexual abuse cases, one of which involved his brother, Liam, a convicted paedophile. He has also been criticised over the way he and other senior Sinn Féin members treated Maíria Cahill, a former party member who alleges she was raped by a suspected IRA member when she was a teenager.

In a Facebook post, O’Connor compared the Sinn Féin leadership to that of the Catholic church and said “elders” in the party should “step down shortly in the same way the last pope did”.

She said of Pope Benedict’s resignation: “It was the smart thing for him to do because his association in people’s minds with frightful things meant the church were losing bums on seats, if I may use a showbiz term.”

O’Connor added: “There’d be a zillion per cent increase in membership of Sinn Féin if the leadership were handed over to those born from 1983-1985 onward and no one associated in people’s minds with frightful things. Frightful things belong where they are now, in the past.”

In the early 1990s, the Dubin-born singer initially expressed support for the Provisional IRA’s campaign but later retracted her comments, saying she was “too young to understand the tense situation in Northern Ireland properly”. In 1993 she took part in protests against an IRA bombing in Warrington that killed two children.

In response to comments on her Facebook post, O’Connor said: “For anyone who is confused, Sinn Féin is no longer associated with the use of violence.”