Daily Mail publisher Associated Newspapers has had to tell journalists and suppliers they are at risk of identity theft after a laptop containing the personal details of thousands of employees was stolen last week.
Associated Newspapers has written to journalists on the Daily Mail, Mail On Sunday, Evening Standard and the Metro after the laptop was stolen.
Parent company Daily Mail and General Trust would not confirm reports that names, addresses, bank account numbers and sort codes had all been lost.
The trust was also unable to confirm whether the laptop was encrypted.
The company said in a statement, "The Daily Mail and General Trust confirms that a company laptop computer containing certain confidential information was stolen last week. The password-protected computer contained limited personal information on some employees and suppliers of the Group's newspaper divisions.
"The Daily Mail and Trust Group has notified police about the incident. It has contacted all those affected and apologised for any inconvenience caused by this breach in security."