A member of parliament was allowed to return to the Labor Party after investigating comments he had made on the party's handling of anti-Semitism charges.
Chris Williamson, a member of Derby North, was suspended in February after saying that Labor was "too apologetic" for criticizing the issue.
A Labor source reported that Mr. Williamson had been found to have violated the party rules and imposed a formal sanction.
They said he could expect further action if he repeated a similar behavior.
A Labor spokesman said the party had "taken all complaints extremely seriously" but could not comment on isolated cases.
After the suspension, Williamson, a close ally of Labor leader Jeremy Corbyn, said he did not want anyone to think he "minimized the cancer of anti-Semitism" and was "absolutely determined" to erase his name.
The Equality and Human Rights Commission is formally considering the work for allegations of anti-Semitism.
The watchdog told the party in March that she had received a number of complaints and was considering the next steps.
But it confirmed in May that there would be an investigation into Labor's "unlawful discrimination, harassment or harassment of people for being Jews."
& # 39; # 39 & shame;
According to a Labor source, the suspension was lifted following a hearing by the party's National Executive Committee (NEC) anti-Semitism panel, which was advised by an independent lawyer.
But national leader of the Jewish labor movement, Mike Katz, said the decision "stinks" and shows the "moral turmoil" in which the party was.
Amanda Bowman, vice-president of the House of Representatives of the British Jews, said it was "a complete shame" to let Mr. Williamson in and that it was "worse evidence" of party anti-Semitism.
And Labor MP Margaret Hodge condemned the decision as "unbelievable," saying the party would "close its eyes to hatred of the Jews."
"This shows that the complaint procedure is a complete deception" she tweeted, "This is not zero tolerance, and every decent member of the Labor Party must question that."
# Red lines & # 39;
The series erupted after Mr. Williamson's footage was published by the Yorkshire Post and showed him how he told activists that Labor had "given too much ground" to allegations of anti-Semitism and was "demonized as a racist, bigoted party ".
The comments came only a week after nine Labor MPs left the party, citing anti-Semitism as one of the main reasons for taking this step.
One of those MPs, Chris Leslie, now a member of Change UK, tweeted his reaction to Williamson's resumption with the hashtag: "#EnoughIsEnough."
He added, "How many more red lines are set up by reasonable Labor MPs just for the leadership to trample on them? What will it bring?"
Independent MP Ian Austin, who also resigned from the party in protest of Corbyn's leadership the same week, said it was "utter shame" to leave Mr. Williamson with a warning after "massively insulting the Jewish people." ,
He added, "This shows the extent to which a party that had such a proud record in the fight against racism was poisoned under Jeremy Corbyn.
"The only question is when decent Labor MPs finally say enough is enough and do something about it."