A Wall Street Journal (WSJ) article has alleged that US authorities are pushing for a settlement of interest-rate rigging allegations with Royal Bank of Scotland Group citing unnamed individuals who it said had been "briefed on negotiations" as its sources.ShareCast contacted the RBS press office and a spokeswoman declined to comment on the WSJ article specifically.The WSJ article claimed that its sources had said the settlement would result in a unit of the British bank pleading guilty to criminal charges in addition to paying a penalty.It reported that RBS executives were resisting any guilty pleas because they were fearful that it could lead clients to cut off activity with the bank and increase exposure to costly litigation.The article further alleged that it would be likely to include approximately £500m in penalties levied by US and British authorities, although the report added that the exact amount remained in flux.RBS' share price was down 5.25% to 348.50p at 12:56 on Tuesday.