Aviva, the U.K.'s second-biggest insurer by market value, mistakenly sent an email dismissing the entire staff at its investment unit before retracting the message.

The email, which was sent to 1,300 employees globally at Aviva Investors, told recipients to turn over company property as they left the building and reminded them of their obligations to guard the firm's confidential information, according to Paul Lockstone, a spokesman for the London-based insurer.

"It was intended that this email should have gone to one single person," Lockstone said by phone. "Unfortunately, as a result of a clerical error, it was sent to all of the Investors staff worldwide."

Most people recognized immediately that the email was a mistake, he said, adding, "From time to time, things go wrong."

The human-resources department issued an apology "fairly quickly" after the message was sent, Lockstone said. News of the mistake was reported Friday by the Daily Telegraph.

Aviva has been scaling back its asset-management business as the European debt crisis and the deteriorating U.K. economy crimps sales.

The insurer said in January it would cut 160 jobs at the unit. Some of the employees affected by that process still haven't departed, Lockstone said.