Labour MP Naz Shah employed as an aide a councillor who posted antisemitic remarks on Twitter.
The Bradford West MP employed Mohammed Shabbir as a member of her staff and gave him a parliamentary email address, it has been claimed.
Mr Shabbir, who represents Labour on Bradford Council, has previously posted tweets about a “Palestinian Holocaust in Gaza” and repeatedly used the term “Zio”.
In a blog post about sex crimes and grooming, he claimed Russian Orthodox Jews were involved in “the sex trafficking trade - demand is particularly high among Charedim, the conservative Orthodox Jews, many of whom are regular clients of brothels…”.
The revelations – on the Guido Fawkes website – came as pressure increased on Labour to take further action against Ms Shah, who stepped down as private secretary to Shadow Chancellor John McDonnell yesterday after a series of social media posts she made about Jews and Israel were revealed.
This morning, Labour leader Jeremy Corbyn issued a statement on the episode.
He said: "What Naz Shah did was offensive and unacceptable. I have spoken to her and made this clear.
“These are historic social media posts made before she was a Member of Parliament.
“Naz has issued a fulsome apology. She does not hold these views and accepts she was completely wrong to have made these posts.
“The Labour Party is implacably opposed to antisemitism and all forms of racism.”
In one august 2014 tweet, Mr Shabbir wrote: "Here is a question - is Isis serving a purpose to create a pretext for Israel to invade Syria and Iraq. Has quest for greater Israel started."
The JC can also reveal that in August 2014, during the Gaza conflict, Mr Shabbir posted a blog about the decision to fly the Palestinian flag at Bradford town hall.
When critics asked why the Israeli flag could not also be flown, Mr Shabbir wrote: “I recognise that for the Israeli people the flag represents different things, for example people like Gideon Levy, the late Israel Shahak or the ever decreasing peace movement there would be, I presume, a patriotism but one that is critical and calling to higher values of justice and truth.
“But also there would be opposing voices. However, many here in Bradford would be nauseated at seeing the Nazi flag or some other fascist with their Nazi salutes and chants.”
He went on to write: “Frankly Israel is a 'terror' and 'apartheid' state, its vexillum has become a symbol of despotism and genocide. In my view there is not an appropriate time to fly this flag in Bradford. One may ask what could be this time?
“Could it be at the return of British Israelis from Gaza with blood on their hands? I think not. Could it be during the holocaust memorial? Many Jews and people will question the conflation of a tragedy and crime like the holocaust with a flag committing another ethnic cleansing. So what is an appropriate time? There is none.”
On Holocaust Memorial Day last year, he wrote about his experience of visiting the Yad Vashem Shoah museum in Jerusalem.
He went on to write that remembering the Holocaust “begs the questions why is the world allowing the Palestinian experience to continue? A nation that was not responsible for the holocaust bears the burden of European anti-Semitism and its guilt.
“We have politicians of all ilks in the UK, including Bradford council, proudly announcing that they are Zionists. I can’t imagine how they can with full knowledge of the atrocities that are taking place in Palestine.
“If we are to take the lessons of the Holocaust seriously we can not trample over the present day freedoms or people. Sadly this seems to be happening all too often. Then there are exceptions like Gerald Kaufman who described the Israelis as ‘acting like Nazis’ have seen the error of their past and have stood up in support of the Palestinian people.”
Mr Shabbir then wrote that he would attend an HMD event where he would be “remembering the Palestinian taxi driver and the thousands that have died in Gaza”.
On his Twitter page, Mr Shabbir features a picture of him with Ms Shah at a Chanucah party at a Bradford synagogue.
Ms Shah’s decision to quit as PPS featured on the front pages of the Mail and The Times today.
In a statement yesterday she unreservedly apologised. She said: “I deeply regret the hurt I have caused by comments made on social media before I was elected as an MP.”