Labour leader Sir Keir Starmer has sacked Rebecca Long-Bailey, saying she shared an article containing an anti-Semitic conspiracy theory.
Mrs Long-Bailey retweeted an interview with actor and Labour supporter Maxine Peake.
The shadow education secretary – who was beaten to the party leadership by Sir Keir – later said she had not meant to endorse all aspects of the article.
But Sir Keir said his “first priority” was tackling anti-Semitism.
The Labour leader said: “The sharing of that article was wrong… because the article contained anti-Semitic conspiracy theories and I have therefore stood Rebecca Long-Bailey down from the shadow cabinet.
“I’ve made it my first priority to tackle anti-Semitism and rebuilding trust with the Jewish community is a number one priority for me.”
A spokesman for the Labour leader added: “Anti-Semitism takes many different forms and it is important that we all are vigilant against it.”
In the article, Ms Peake discussed the police killing of George Floyd in Minneapolis.
She said: “The tactics used by the police in America, kneeling on George Floyd’s neck, that was learnt from seminars with Israeli secret services.”
The Independent article also quoted the Israeli police denying Ms Peake’s claim saying: “There is no tactic or protocol that calls to put pressure on the neck or airway.”
Later on Thursday, Ms Peake tweeted that she had been “inaccurate in my assumption of American police training and its sources”.
She added: “I find racism and anti-Semitism abhorrent and I in no way wished, nor intended, to add fodder to any views of the contrary.”