The Obama administration on Thursday formally blamed Iranian hackers for a coordinated campaign of cyber attacks from 2011 to 2013 on dozens of U.S. banks and a New York dam.

The Justice Department unsealed an indictment against seven Iranians believed to have been working on behalf of the Iranian government and described as "experienced computer hackers."

At least 46 major financial institutions and financial sector companies were affected by the hacking campaign, according to the indictment. 

Reuters (Reporting by Dustin Volz; Editing by Chizu Nomiyama)