A data breach at large UK software company Sage may have compromised personal information for employees at 280 UK businesses, it is understood.
Police are investigating the breach and Sage is probing the "unauthorised access" of data by someone using an "internal" company computer login.
The information was accessed at some point over the past few weeks.
It is unclear whether it was stolen from the FTSE-listed firm, or merely viewed.
The company, which provides business software for accounting and payroll services to firms across 23 countries, says it is taking the breach extremely seriously.
The police are investigating and the Information Commissioner's Office (ICO), responsible for the enforcement of the Data Protection Act 1998, has been informed.
Sage has notified those businesses whose data may have been accessed and has advised them to look out for any unusual activity.
A Sage spokesperson said: "We are investigating unauthorised access to customer information using an internal login.
"We cannot comment further whilst we work with the authorities to investigate - but our customers remain our first priority and we are speaking directly with those affected."
Sage was founded in 1981 and now has more than 13,000 employees around the world.
The group has an annual turnover of £1.3bn, and is the only remaining technology stock on the FTSE 100.
If the ICO decides that Sage has been negligent there are a number of actions it could take, including criminal prosecution, non-criminal enforcement, or undertaking an audit at the firm.