Diane Abbott has retweeted a number of critical messages about the Labour Party's deputy leader, Tom Watson.
The shadow home secretary shared a series of tweets in quick succession about Mr Watson's treatment of the party's general secretary Jennie Formby, regarding allegations of antisemitism within Labour.
Mr Watson had written to Ms Formby, who is undergoing cancer treatment, to ask for her to publish information it sent to the UK's equality watchdog, which was investigating the anti-Jewish abuse claims.
But she insisted that she had offered him the chance to view the submission, and accused him of "traducing her".
Mr Watson also alleged that Ms Formby had deleted emails relating to certain cases - which Ms Formby has denied.
Among the tweets Ms Abbott shared to her official Twitter account included one from Labour MP Emma Dent Coad.
"Solidarity with Jennie Formby. On the day a report on parliamentary bullying is published, Watson has been relentless. Shame on him," the tweet read.
Another, also retweeted by Ms Abbott, said: "Appalled to find Tom Watson publicly attacking Jennie Formby simply for doing her job with her usual integrity and professionalism, protecting confidentiality of a sensitive investigation. Deputy leader should support our staff, not undermine them - especially at difficult time."
Mr Watson's letter followed the airing of a BBC Panorama documentary about the party's handling of antisemitism allegations.
Four ex-Labour staff broke non-disclosure agreements to give testimonies, including the party's former general secretary Iain McNicol.
The Labour Party submitted a written complaint to the BBC over the documentary.