More than 1,000 emails sent by the Metropolitan Police have accidentally shared the email addresses of victims of crime with others, the force said.
The mistake was caused by "human error" when a quality control survey was sent by email on Monday.
A Scotland Yard spokesman said: "We can confirm that the Metropolitan Police Service has inadvertently shared the email addresses of a number of victims of crime with other victims.
"The sharing of the data was the result of human error and occurred on Monday January 30 when the Crime Recording and Investigation Bureau (Crib) project was emailing out a survey to ensure that victims were receiving a better service as part of the MPS creation of a single telephone investigation unit for London."
The spokesman added: "In total 1,136 emails were sent out in seven batches of between 119 and 198 recipients but because the addresses were put in the wrong box they were visible to the other recipients in the batch.
"No other personal details were revealed and we are contacting everyone affected to explain what happened and to apologise."
The Met said it was reviewing how it carries out surveys in a bid to avoid similar mistakes being made in the future.
The Information Commissioner's Office has been informed.