The payday loan firm Wonga has suffered a data breach which may have affected up to 245,000 customers in the UK.

The firm said it was “urgently investigating illegal and unauthorised access to the personal data of some of its customers”.

The firm said it began contacting borrowers on 8^th April 2017 and was offering support through a dedicated phone line.

The information stolen includes names, addresses, phone numbers, bank account numbers and sort codes.

Prof Alan Woodward, a cybersecurity expert at the University of Surrey, said it was “looking like one of the biggest” data breaches in the UK involving financial information.

The range of information stolen may also include the last four digits of customers’ bank cards – information used by some banks as part of the login process for online accounts.

The payday lender has set up a help page for affected customers. It advises them to:

• Alert their bank and ask them to look out for any suspicious activity. Wonga will also be informing financial institutions about the breach
• Watch out for scammers or unusual online activity. In particular, customers are told to be cautious about cold calls and emails asking for personal information
• Contact the Wonga helpline on 0207 138 8330 for further questions