A notice on the Sage UK company website states:
We believe there has been some unauthorised access using an internal login to the data of a small number of our UK customers so we are working closely with the authorities to investigate the situation.
Our customers are always our first priority so we are communicating directly with those who may be affected and giving guidance on measures they can take to protect their security. If you have any concerns at all, you can reach us on the following contact details.
Independent, unverified news reports, state that less than 300 UK customer accounts may have been exposed through an internal login.
Sage is a global vendor for integrated accounting, payroll and payment systems, supporting the ambition of the world’s entrepreneurs. Sage has 13,000 employees and supports millions of entrepreneurs across 23 countries. The group has an annual turnover of £1.3bn.