Royal Bank of Scotland is to set aside more than £3 billion in additional funds to cover litigation and customer compensation claims, the state-backed lender disclosed today.
The sum includes £1.9 billion to cover mainly US action over mortgage-backed financial products.
There will also be an extra £465 million to cover a redress scheme for customers mis-sold payment protection insurance (PPI).
The group has set aside an extra £500 million in relation to allegations over the mis-selling of complex financial products, known as interest rate swaps, to small firms.
There will also be an additional £200 million of provisions "for various conduct related and legal expenses" when fourth quarter results are published next month, said the bank, which is 80% taxpayer owned.
Chief executive Ross McEwan said: "At the peak of the financial crisis, RBS was the biggest bank in the world.
"When the crisis broke the bank was involved in a number of different businesses in multiple countries that have subsequently faced heavy scrutiny by customers and regulators.
"The scale of the bad decisions during that period means that some problems are still just emerging. The good news is we are now a much stronger bank and can manage these costs while still supporting our customers."
The bank also confirmed that its executive committee would not receive bonuses for their performances in 2013. The announcement applies to eight senior employees. Mr McEwan has already said he would not take a bonus for 2013 or 2014.
The extra £1.9 billion for mortgage-backed securities was announced "following recent third party litigation settlements and regulatory decisions".
In November, the US Government and JP Morgan Chase agreed a record 13 billion US dollar (£7.8 billion) settlement over its sales of poor quality mortgage-backed securities that collapsed in value during the financial crisis.
Meanwhile in the same month, an RBS subsidiary agreed to pay 153.7 million US dollars (£95.5 million) to settle a US probe into allegations it misled investors over what was described as a "shoddy" subprime mortgage product.
In relation to PPI, RBS said claims had continued at the same rate as before - £225 million per quarter - rather than an expected decline, and that they were now anticipated to continue for a longer period.
The total provision for the PPI compensation scheme now stands at £3.1 billion, of which £2.2 billion had been used up by the end of 2013.