Data protection and storage firm Iron Mountain has admitted losing backup tapes for two of its customers.
Tapes containing the private information of employees of the Long Island Rail Road company (LIRR) were lost during "a routine delivery" in early April, said Iron Mountain, which handles and stores backup data for companies.
Other tapes belonging to a different company were also lost, but did not contain sensitive data, Iron Mountain said. The name of the client was not disclosed.
Investigations by Iron Mountain in collaboration with the New York Police Department (NYPD) and the Metropolitan Transportation Authority (MTA) found the loss was probably an accident, although foul play was initially suspected.
"While the case was opened as a potential burglary, the collaborative investigation between the NYPD, the MTA police and Iron Mountain's own security organisation has found no information to suggest the backup tapes were misappropriated in any way," the company said.
Current, past, and retired employees of LIRR have been notified that their personal data has been lost, in accordance with New York State law.
The data protection firm denied personal information could be misused as a result and said it was "unlikely" to lead to identity theft.
"There is no evidence to suggest the information on the backup tapes has been accessed by unauthorised persons," Iron Mountain said. "It is unlikely that someone interested in stealing identities would ever target backup tapes because the information would be too difficult to access and read; it would require highly specialised expertise, specific software and sophisticated technology equipment."
This is not the first time Iron Mountain has lost sensitive customer information. Last July the company lost a container of backup tapes from several banks containing the account details of banking customers.
Those tapes belonged to a Texas-based ISP that hosted a software application used by the banks, and were lost while being transported from a data processing company to storage.
In March last year Iron Mountain lost computer tapes containing the personal information of about 600,000 current and former Time Warner employees.