Standard & Poor's says it is to be sued by the US government over the credit ratings agency's assessment of mortgage bonds before the financial crisis. The agency said that the civil lawsuit would focus on Standard & Poor's high ratings in 2007 for some mortgage-backed securities that later collapsed in value. Standard & Poor's says the case is entirely without factual or legal merit. The suit would be the first such case over alleged wrongdoing by a ratings agency tied to the financial crisis. The agency said the justice department had informed them of the impending civil suit although the federal agency declined to comment. The Wall Street Journal reports that the move follows a breakdown in talks between the justice department and Standard & Poor's .Shares in Standard & Poor's owner, the US publishing and media group McGraw Hill, fell 14 per cent on Wall Street yesterday following the announcement while those in fellow ratings agency Moody's fell 10 per cent indicating the market expects that they may be next in the justice department's sights.Standard & Poor's and other agencies have faced criticism from investors, politicians and regulators for assigning their top AAA ratings to thousands of subprime and other mortgage securities that later collapsed in value. The firm says it deeply regrets how its ratings failed to anticipate mortgage market conditions as the financial crisis hit and that it has since spent 400 million dollars to help bolster the quality of its ratings.