An employee of software firm Sage has been apprehended by police in London following a breach last week in which it is believed the personal information of between 200-300 of the company's customers in the U.K. was stolen.

The suspect, a 32-year-old woman, is accused of conspiracy to defraud Sage, according to a Reuters report. While she was nabbed at Heathrow Airport, she has not been charged and was released.

It is not yet known exactly what data was pilfered. The Newcastle-based provider of accounting and payroll software is one of Britain's biggest technology firms with three million business customers worldwide. The company stores a wide variety of data on its clients. It was reported that among the information stolen was bank account and salary details.

Sage believed the theft was an inside job as employee credentials were used to login and gain access to the data.