Barclays is in talks with regulators, customers and UK authorities over claims confidential details of clients had been stolen and sold.The data is from 2008 or earlier and is linked to a financial-planning unit that was shut in 2011, company spokeswoman Carey Withey told Bloomberg.Withey said the bank is taking "all necessary steps" to contact the customers affected. Her remarks come after the Mail on Sunday said as many as 27,000 customer files containing personal and financial information were taken, according to a whistle-blower.It is understood the files included details on mortgages, health issues, income, savings, insurance policies, passport and national insurance numbers.The anonymous whistle-blower handed the newspaper a memory stick containing files on 2,000 customers and had told it that each of the 27,000 files could be sold for as much as £50.The newspaper added that the data was sold to brokers to be used for "investment scams". It was unclear how the files were stolen. The news comes ahead of the bank's full-year results on Tuesday.Barclays said on Monday it will announce adjusted profit before tax for 2013 of £5.2bn, down 25% from 2012 and under the £5.4bn average forecast from analysts polled by the bank.Barclays also said it will report a statutory profit before tax of £2.9bn.Shares rose 1.18% to 274.90p at 10:40.RD