CNN reports that the public apology, printed in papers including the Financial Times and the Times of London and signed by outgoing chairman Marcus Agius, says the bank is 'truly sorry for what has happened and that you have been let down'.
Here's the full text of the apology:
'To all Barclays customers and clients,
We are truly sorry for what has happened and that you have been let down.
It is our actions now and over the coming months and years that will make the difference.
You are the lifeblood of our business, and we will not allow ourselves to be distracted from what really matters – delivering for you, day in and day out.
My colleagues work tirelessly to do just that. The Board and I thank them for their commitment and for their determination to ensure that customers and clients are at the heart of everything we do.
I also thank you for your business. It is our responsibility to earn the right to retain it'.