Jeremy Corbyn was plunged into a new antisemitism row after an interview where he failed to outline costings for his childcare policy.

The Labour leader was left floundering after Emma Barnett, the BBC's Woman's Hour host, asked him to lay out how much the policy would cost.

When he failed to answer she revealed he was logging on to his iPad and flicking through his own party manifesto to try and remember the figure.

'It will obviously cost a lot...we accept that,' he said before asking: 'Can we come back to that in a moment?'

But after the interviews Barnett, an orthodox Jew, was subject to antisemitic abuse online by Corbyn supporters.

One user, David Carter from Cardiff, who according to The Times has previously shared Holocaust denial websites, posted: 'Zionist Emma Barnett (family lived off the proceeds of brothels) . . . Who would have thunk it.'

Blogger Phillip David Jones, who runs the @labourinsider feed, tweeted: 'Breaking news. Allegations have surfaced that @emmabarnett is a zionist. Are the allegations true Emma?'

Later Barnett tweeted:

Later Corbyn rebuked those abusing Barnett. 

'Journalists . . . do a job that does require asking difficult questions . . . Under no circumstances whatsoever should anyone throw personal abuse at anyone else because they are doing the job that they have been employed to do and I will not tolerate it.'

It comes the same day a poll put the Conservatives 64-points ahead among Jewish voters.

The Survation study for the Jewish Chronicle shows just 13 per cent of Jewish voters plan to back Labour at the election in nine days time, compared to 77 per cent for the Conservatives.

But it also found more than half who will not back Labour say they would reconsider if Corbyn was not leader.

In an attempt to tackle the perception Corbyn's leadership fuels antisemitism, Labour launched a 'race and faith' manifesto on Tuesday, promising to tackle hate crime and recruit 10,000 more police officers to work on community beats.

'Anti-Semitism is an evil which led to the worst crimes of the twentieth century. Every one of us has a responsibility to ensure that it is never allowed to fester in our society again,' it reads.