The Metropolitan Police is expected to refer itself to the Information Commissioner after accidentally sending an email which named alleged victims of the Westminster “honeytrap” scandal.

The force is investigating flirtatious messages being sent by someone calling themselves “Charlie” or “Abi” as many as 20 people including MPs, staffers and political journalists.

A detective sent potential victims an email updating them on the case, but inadvertently copied in all of those involved, revealing to the recipients their names and email addresses.

The Met is aware of the apparent data breach and has been asked by the BBC for a response.

The email was sent on Friday afternoon to update 18 people that the date a suspect would have to answer bail was being changed because of a fire at Charing Cross police station.

However, the sender, a detective sergeant in the Met’s Diplomatic and Parliamentary Protection unit, included the recipients’ names in the CC section of the email, rather than BCC, which would have concealed their identities.

The BBC has seen the email, and will not be naming those included as recipients, however they include members of parliament, political journalists and Commons staff.

A senior Met source accepted a data breach of this kind would normally result in a referral to the Information Commissioner, who has the power to issue penalties or fines under data protection laws.

One of the alleged victims told the BBC: “It’s infuriating to have your personal details released in this way.

“It will make me think twice about reporting anything to the Met again.”

A Labour staffer was arrested by police on suspicion of harassment and committing offences under the Online Safety Act in June this year.

Former Conservative MP William Wragg has spoken out about how he was left suicidal after feeling pressured into sharing others’ details.