Jeremy Corbyn is facing mounting pressure from cross-party politicians - including one of his frontbenchers - to suspend a Labour MP over antisemitic posts on social media.
It comes as the Labour leader called in Naz Shah, the Bradford West MP, for a personal reprimand a day after she quit as an aide to shadow Chancellor John McDonnell and apologised for apparently endorsing the relocation of Israelis to the US.
David Cameron, speaking at Prime Minister’s questions, said it is “quite extraordinary” that Ms Shah has not already been suspended.
In a Facebook post in 2014, before she became MP for Bradford West, Ms Shah shared a graphic which showed an image of Israel's outline superimposed onto a map of the US under the headline "Solution for Israel-Palestine Conflict - Relocate Israel into United States", with the comment "problem solved".
The Labour leader said Ms Shah "does not hold these views" and insisted the party was "implacably opposed to anti-Semitism and all forms of racism" as he faces pressure to act on concerns of increasingly-open anti-Semitism within the ranks.
But he did not take any further disciplinary action despite his office having been told by shadow energy secretary Lisa Nandy that procedures must be applied "without exception".
Ms Nandy told BBC2's Daily Politics: "I made clear my view to the leader's office that we should suspend anybody who makes anti-Semitic remarks, in line with our policy, and investigate.
"It is right that we look at the circumstances around what has happened. But I think our policy is absolutely clear that we suspend people and then investigate.
"There is a real problem for the Labour Party if we don't look like we are taking these things seriously. But this is not just about the impact on the Labour Party, there is also the question here about what is the right thing to do.
"And the right thing to do here is to make sure that we do not tolerate anti-Semitism at all."
In a second apology, Ms Shah wrote in Jewish News that she wished to make an "unequivocal apology for statements and ideas that I have foolishly endorsed in the past".
"The manner and tone of what I wrote in haste is not excusable. With the understanding of the issues I have now I would never have posted them. I have to own up to the fact that ignorance is not a defence.
"The language I used was wrong. It is hurtful. What's important is the impact these posts have had on other people. I understand that referring to Israel and Hitler as I did is deeply offensive to Jewish people, for which I apologise.
She said she hoped she could "win back your trust and faith in me".
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