Three people have been arrested by police investigating alleged anti-Semitism among Labour Party members.
Scotland Yard said two men in their 50s and a woman in her 70s had been arrested during March on suspicion of publishing or distributing material likely to stir up racial hatred.
All three have been released pending further inquiries.
The Labour Party said it welcomed the police investigation as anti-Semitism “has no place in our society”.
The investigation was launched after radio station LBC obtained a leaked Labour dossier detailing anti-Semitic social media messages allegedly posted by party members.
The radio station handed the dossier to Metropolitan Police Commissioner Cressida Dick following an interview in September.
A formal inquiry was announced in November, when Ms Dick made it clear the Labour Party itself was not under investigation.
In a statement, Scotland Yard said the dossier’s contents had been examined by specialist officers.
It added that they were interviewed under caution before being released under investigation.
A Labour Party spokesman said: “We welcome the police investigating these individuals’ alleged crimes.
“Anti-Semitism has no place in our society and we are committed to challenging and campaigning against it in all its forms.”