More than 2,000 Morrisons staff are to sue the supermarket for damages after financial details relating to employees were posted online by a disgruntled auditor, lawyers say.
Andrew Skelton, who is in his 40s, was given an eight-year jail term in July after being found guilty of leaking sensitive, personal data relating to almost 100,000 of the supermarket's staff, following a trial at Bradford Crown Court.
Lawyer Nick McAleenan, who is representing Morrisons' staff taking legal action, says the claim will have implications
And Mr McAleenan, a data privacy specialist at JMW Solicitors, said more staff could join the group taking legal action in coming months.
"My clients' position is that Morrisons failed to prevent a data leak which exposed tens of thousands of its employees to the very real risk of identity theft and potential loss," said Mr McAleenan.
"In particular, they are worried about the possibility of money being taken from their bank accounts and - in the case of younger clients - negative consequences for their credit rating."
Lawyers say they do not yet know the size of a total claim.
Mr McAleenan said the claim had implications for employers and employees.
"Whenever employers are given personal details of their staff, they have a duty to look after them," he said.
"That is especially important given that most companies now gather and manage such material digitally and, as a result, it can be accessed and distributed relatively easily if the information is not protected."
Skelton, who was a senior internal auditor at Morrisons, had posted data on the internet and sent it to newspapers due to a ''grudge'', jurors heard.
He had leaked information in response to a warning after the company found out he used the mail room at Morrisons' headquarters in Bradford to send out eBay packages.
The data breach cost Morrisons more than £2 million to rectify.
Skelton, from Liverpool, was found guilty of fraud by abuse of position, unauthorised access to data with the intent of committing an offence and disclosing personal data, the Crown Prosecution Service said.
Data containing information including salaries, national insurance numbers, dates of birth and bank account details were sent to The Guardian, Trinity Mirror Newspapers and the Bradford Telegraph & Argus last year and uploaded to data-sharing websites, jurors heard.