Barclays PLC has set aside another 700 million pounds ($1.1 billion) to compensate customers who bought payment protection insurance which they didn't need.

The bank's announcement on Thursday raised its total provision for mis-selling insurance to 2 billion pounds, which it said is still only a best estimate.

The unscheduled announcement came ahead of the bank's third-quarter earnings report due on Oct. 31.

Other big British banks face losses on the insurance sales. Lloyds Banking Group has made provisions of 4.3 billion pounds, HSBC has set aside 1.3 billion pounds and Royal Bank of Scotland 1.5 billion pounds.