Vodafone is the latest organisation to be added to the list of Deloitte customers affected by a laptop stolen from the accountacy firm.
A laptop containing the personal details of around 100,000 pension scheme members was stolen from an employee of Deloitte.
It was previously known the computer held the names, National Insurance numbers and salaries of Network Rail and British Transport Police pension scheme members. It also contained details of BSkyB employees.
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Vodafone said it was "concerned" about the pension details of its staff being stolen, and was in discussion with Deloitte about the security of its data.
Deloitte said the laptop was password protected and also encrypted. There was, therefore, a "very low risk" of the details being accessed, said Deloitte.
No addresses or bank account details were contained on the laptop.
The laptop was stolen last month from a "public place", but has only recently come to light.
Deloitte has refused to make public the list of organisations affected by the loss, but they are continually leaking out anyway.