Royal Bank of Scotland today revealed an additional £400m sterling charge to cover the cost of mis-sold payment protection insurance (PPI) claims.
This brings the total bill PPI to £1.7 billion.
RBS also said today that the cost of its recent IT glitch had risen by £50m to £175m.
The mounting provisions came as the bank, which has 30 million customers worldwide, unveiled a pre-tax loss of £1.3 billion, compared to a £2 billion profit the same time last year.
RBS said that of the £1.2 billion in impairment charges it has suffered over the past three months, just under half a billion occurred at Ulster Bank.
RBS chief executive Stephen Hester said the bank's five-year restructuring plan is now in its later stages and is being worked through successfully.
"We have already made much progress, though clearly not enough, and our reputation will take time to recover from past events which are still being accounted for,'' he said.
The additional provisions overshadowed underlying progress at the bank. The group's core businesses - what will become the "new" bank - saw operating profits rise 67% year-on-year in the third quarter to £1.6 billion.
The non-core assets fell by a further £7 billion to £65 billion in the quarter and have been reduced by 75% to date, while its bad-debt losses fell by £159m from the previous quarter to £1.2 billion.
Staff costs were 5% lower than in the second quarter at £1.9 billion, with total headcount down by 9,900 or 7% from a year earlier.
The group cleared two major milestones in the three month period, floating its insurance arm Direct Line Group in October, raising £911m from the sale of a 34.7% stake, and it exited from the UK government's Asset Protection Scheme.
However, the bank did see an expected branch sale to Santander collapse in the quarter, which it said was "disappointing". It has restarted efforts to sell the business.
The total mis-sold PPI bill for Britain's big four lenders has risen to more than £10 billion, with HSBC forecast to post a more modest provision next week. Fellow state-backed lender Lloyds Banking Group yesterday set aside another £1 billion to cover PPI claims, bringing the total to £5.3 billion, while Barclays announced an additional £700m, giving it a total of £2 billion.
