Royal Bank of Scotland Group said it will take a £3.1 billion ($3.8 billion) charge in its fourth-quarter results in order to provide for likely fines following a probe in the US into sales of mortgage securities. The bank said it is continuing to cooperate with the US department of justice on its investigation, though timing of a settlement remains uncertain. RBS has now taken £6.7 billion of provisions related to as many as 15 mortgage investigations and lawsuits, and said further charges may still be needed. The bank is among the final global lenders yet to settle in a year-long probe that has garnered more than $50 billion in penalties for the department of justice since it began investigating the pre-crisis sale of mortgage bonds.