The arrest follows Sage’s disclosure last week that data about more than 200 of its U.K. customers had been stolen, with an employee rather than external hackers being responsible.

On Wednesday, the City of London Police arrested a 32-year-old woman at Heathrow Airport. The woman has since been bailed.

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The information that was taken reportedly included bank account and salary details. Sage is a major supplier of accounting and payroll software for small and medium-sized firms.

The company, based in Newcastle, said someone used an internal login to access the data without authorization.

After the revelation, Sage’s share price dropped around 4%, though it mostly recovered afterwards.

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The fact that the breach was internal must have come as some relief. The British telecoms provider Talk Talk suffered a severe data breach last year that was the work of hackers, leading to an immediate 10% hit to its share price.