The Labour Party has received 673 complaints in 10 months alleging acts of anti-Semitism by its members.
A letter from the party's general secretary, Jennie Formby, revealed the figures after she was pushed by MPs for specific details.
She said 96 members were immediately suspended from the party for their conduct between April 2018 and January 2019, and 12 were expelled.
But in a letter, a group of MPs said there was still a lack of information.
Labour has struggled to contain a long-running row over anti-Semitism.
At a meeting of the Parliamentary Labour Party (PLP) last week, MPs unanimously passed a motion urging the leadership to do more to tackle it.
They also called for specific details about how many people were being investigated, how many letters had been written to those accused telling to them to desist and what punishments had been given.
Ms Formby said: "I totally reject the suggestion that the existence of anti-Semitism in our party is a smear. I have seen hard evidence of it and that is why I have been so determined to do whatever is possible to eliminate it from the party."
But Labour MP Dame Margaret Hodge tweeted a warning not to trust the figures and said she was not convinced the party's leadership were "serious on rooting out anti-Semitism".
Ahead of Monday's PLP meeting, Ms Formby, who did not attend, wrote to MPs to provide more detail.
She said the party's National Executive Committee (NEC) previously believed that statistics on disciplinary matters should remain confidential and not be published.
But after MPs rejected her proposal of having three elected members monitoring the figures regularly, she said she "pushed hard" to get the NEC to agree to publish them.
The data published revealed:
- 673 complaints of anti-Semitism by Labour Party members were received - a Labour spokesman said this represented about 0.1% of the membership
- 96 members were immediately suspended after complaints were made and a further 211 were told they would be investigated
- 146 members received a first warning, and 220 cases did not have sufficient evidence of a breach of party rules for an investigation
- Of the 307 who were suspended or notified of an investigation, 44 members left the party
- Another 96 were referred to the party's anti-Semitism Disputes Panel
- Of the 96, 16 members were issued with a formal warning from the National Executive Committee, six members' cases were referred for further investigation, 25 members were issued with reminder of conduct (a first written warning), and seven members' cases were closed as the full evidence suggested no further action should be taken
- The panel decided to refer the other 42 members to Labour's National Constitutional Committee (NCC), with five members leaving before their cases were reviewed
- Of the 37 cases referred to the NCC, 12 members were expelled and six received sanctions, while the rest await their outcome
- The other members who were suspended or notified of an investigation are either still under investigation or are cases where the investigation revealed evidence that meant the case could not be pursued further
- The party received a further 433 complaints which were not about Labour party members
By Iain Watson, BBC political correspondent
If the Labour leadership believed that producing statistics on anti-Semitism cases would quell internal criticism, then they called it wrong.
Labour MPs who had pushed for the figures to be made public, then questioned their veracity.
And some criticised the party hierarchy for expelling so few members - 12 - who had breached the rules.
The Labour leader was also criticised for not being present at tonight's parliamentary party meeting to discuss the issue.
So flames of discontent have been fanned not extinguished.
Party spokespeople point out only 0.1% of a mass membership have been accused of anti-Semitism.
But one veteran MP, who has spent many years on the front bench, thinks all this won't end well. He told me: "The whiff of a breakaway is in the air".
Dame Margaret, who has been outspoken on the party's handling of the issue, raised concerns on Twitter about the figures.
Glad to see labour leadership comin up with some stats. But I alone put in over 200 examples, some vile, where evidence suggested they came from Labour. So don’t trust figures. Can’t believe only 12 expulsions. Not convinced leadership serious on rooting out anti Semitism— Margaret Hodge (@margarethodge) February 11, 2019
Following Monday's meeting of the PLP, a letter addressed to Jeremy Corbyn and signed by seven Labour MPs, including Dame Margaret, Luciana Berger and John Mann, accused the leadership of not respecting the PLP motion for more information on anti-Semitism cases.
The letter called for a vote on it at Tuesday's shadow cabinet meeting, as "no-one from the leadership presented the information requested", saying: "The party should respect the mandate of the PLP's resolution".
It lists eight points where the MPs believe there to be a lack of information, including the amount spent on legal counsel and the fact that only nine months' worth of data was released.
Questioning the figures provided, Dame Margaret told the BBC if she had submitted 200 complaints alone, the official figure of 673 complaints against party members suffered from "a total lack of credibility".
She said she was "depressed" and "genuinely upset".
Labour MP Catherine McKinnell said there was a question mark over the "inability to produce data that predates 2018".
"The data we have does reveal the use of 'reminders of conduct' as a way of resolving a complaint without an investigation - it's not clear what criteria is being used," she said.
"Somebody from the leadership needs to come so we can ask the questions and get some answers. We have ongoing concerns."
Labour MP Ruth Smeeth - who has suffered anti-Semitic abuse - added: "This is not over."
BBC political correspondent Iain Watson said that during the private PLP meeting, Louise Ellman - president of the Jewish Labour Movement - raised the details of a specific case where she believed insufficient action had been taken.
The former party general secretary Iain McNicol defended his record in tackling anti-Semitism before Ms Formby took over, our correspondent added.
A party spokeswoman said that Ms Formby would attend a future meeting when available.