Stephen Hester, the chief executive of RBS, said he would be "disappointed" if he did not have more news on the scale of the Libor fine by the time the bank reports its full-year results in February.
The bank, just over 80% owned by the taxpayer, is yet to give any indication of the size of any fine or if it will be larger than the £290m penalty paid by Barclays to the Financial Services Authority and regulators in the United States.
Even if the fine is smaller, Hester said it would be a "miserable day in RBS's history".
The "explosive" reaction to the Barclays fine – which forced the departure of the chief executive Bob Diamond – may have been a factor in the seeming delay in the approach of regulators to future penalties, he said.
RBS took an extra £400m provision for PPI compensation – now regarded as the costliest mis-selling scandal in history – taking its total to £1.7bn. But this is a "best guesstimate" and could yet rise as the finance director, Bruce van Saun, admitted the bank had been "guilty of underestimating the response rate" from customers.
The PPI provision helped push the bank to a £1.2bn loss in the third quarter versus a £2bn profit a year ago, while for the nine months the bank reported a £2.7bn loss, against £1.2bn profit a year ago.
Hester, who was parachuted in to run the bank in October 2008 when Fred Goodwin was ousted, said the bank's restructuring plan would be completed by the time of the next election in 2015 but any share sale by the government was likely to depend on economic growth and the share price.
"Plausibly we can be ready before the election," said Hester.
The shares were flat at 293p in early trading – well below the 500p average at which the near-80% stake was bought, a loss of around £18bn.
"The five-year restructuring plan is now in its later stages with important work still to do, including an emphasis on dealing with reputational issues now that the bank's safety and soundness has advanced so well," Hester said.
"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."
Asked if any bankers had been disciplined for the PPI scandal, Hester said all the senior managers had left and that claw back of bonuses was not included in contracts until 2009.
"The industry has to take its medicine on PPI," said Hester, who has already axed sales targets linked to bonuses for branch staff.
Hester has made clear he will not take any bonus for 2012 because of the IT meltdown in the summer which has now cost the bank another £50m, taking the total charge to £175m.
The bank, which has axed 9,000 staff in the last 12 months and 37,000 since the 2008 crisis, is being forced to sell off parts of its business to meet EU rules linked to the £45bn taxpayer bailout.
RBS has made progress on disposing of Direct Line, floating a third of the business on the stock market, but has run into difficulty with the sale of 316 branches to Santander, which pulled out last month. Hester said RBS was unlikely to ask the EU to reverse its decision and that the sales process had been resumed.
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