The Metropolitan Police has arrested three people in its criminal investigation into allegations of antisemitism against Labour members.

The Met opened a criminal investigation into alleged antisemitism by Labour members, after LBC passed on an internal party dossier detailing allegations to the Met Commissioner Cressida Dick last year live on-air at its studios.

The dossier contained alleged Jew-hate by 45 party members. One of them was a threat to give a "Zionist extremist MP" a "good kicking". The party was condemned for its "inexplicable" failure to inform those who were threatened.

Adam Langleben, a Jewish former Labour councillor, said the arrests may prove damning for the party, which he said “neglected to inform the MPs who threats were made against and only acted once the details were leaked”.

In a joint statement, the Board of Deputies, the Jewish Leadership Council and CST said: "We await the outcome of the investigations, but ask why Labour had not itself alerted the police.

"We are also concerned as to how many more cases remain unknown and repeat our request, made one year ago to Mr Corbyn, that the party urgently appoint an independent ombudsman on such matters.”  

In a statement on Thursday morning, the Met said it had arrested two men in their 50s and a woman in her 70s.

The first man in his 50s was arrested on March 7, on suspicion of an offence contrary to Section 19 of the Public Order Act – publishing or distributing material likely to stir up racial hatred.

He was arrested after a warrant was “executed at an address in Birmingham”, police said.

A Met spokesperson said: “He was interviewed under caution at a custody suite. He has been released under investigation.”

The Met said a second man was arrested, in Tumbridge Wells on March 14 for the same charge and has also been interviewed under caution and released under inverstigation.

A woman in her 70s was arrested on March 21, also on suspicion of publishing or distributing material likely to stir up racial hatred after a warrant was “executed at an address in Wandsworth”.

The Met said: “She was interviewed under caution at a south London police station. She has been released under investigation.”

A Labour spokesperson welcomed the “police investigating these individuals’ alleged crimes".

They said: “Antisemitism has no place in our society and we are committed to challenging and campaigning against it in all its forms.”

It is understood the three people arrested are no longer members of Labour but they were party members when Ms Dick was handed the dossier in September, LBC political editor Theo Usherwood said.

The Met opened a criminal investigation into alleged antisemitism by Labour members, in November after the dossier's contents were examined by "specialist officers".

At the time, it said: "A criminal investigation has commenced into some of the allegations within the documentation.

"Early investigative advice is being sought from the Crown Prosecution Service. The MPS will not comment further on the details of our investigation."

LBC had asked Mak Chisty, a former police commander who used to run its hate crime unit, review its dossier.

He concluded that four of the cases constituted race hate crimes and seventeen more could be deemed hate crimes after the investigation.