A member of Labour's ruling National Executive Committee has warned Jeremy Corbyn that the party's new procedure for dealing with complaints of sexual harassment is "insufficient".
Under the new process, drawn up in the wake of a wave of allegations and rumours relating to improper behaviour at Westminster, grievances would be reviewed by a specialist panel appointed by the NEC.
But NEC member Jasmin Beckett has now written to the Labour leader urging him to consider setting up a fully independent body to deal with sensitive complaints.
Her warning came as Mr Corbyn was criticised by a prominent Labour backbencher for promoting Kelvin Hopkins to the shadow cabinet last year after a young activist had raised allegations about his behaviour.
The Luton North MP has been suspended from Labour while an investigation into claims that he sent suggestive texts and acted inappropriately is carried out.
Ava Etemadzadeh (27) initially complained to the whips' office following contact with Mr Hopkins around three years ago, and said she was "very disillusioned" about his subsequent promotion.
It is understood that the MP was spoken to about why his behaviour was inappropriate and reprimanded by then chief whip Dame Rosie Winterton when Ms Etemadzadeh made her initial complaint after dealings with Mr Hopkins in 2014 and 2015.
But he was appointed culture spokesman in June 2016 following mass resignations which were part of a botched coup attempt against Mr Corbyn.
Birmingham Yardley MP Jess Phillips told BBC Radio 4's Today programme: "I am a bit concerned about the fact that Kelvin was then promoted afterwards, that does seem wrong to me... I think that people just didn't take it as seriously as it needed to be taken."
Ms Etemadzadeh told BBC Radio 4's World at One her complaint was taken seriously by then chief whip Dame Rosie Winterton, but not by the leader's office.
She said the decision to suspend Mr Hopkins came just minutes before the Daily Telegraph published an account of her story.
Mr Hopkins is the latest MP to become caught up in a wave of allegations over sleaze in Westminster.
Sir Michael Fallon, who quit as defence secretary on Wednesday after admitting that his behaviour had "fallen below the high standards required" in the role, was reportedly forced out after Cabinet colleague Andrea Leadsom passed a dossier of claims to Number 10.
Sources close to the Tory MP said he "fundamentally denied" claims that he made a crude joke to the Commons Leader, while Mrs Leadsom's team and Number 10 declined to comment.
Mrs May has called a meeting of all party leaders on Monday to agree a new system of dealing with abuse complaints in Parliament.
