The Treasury Department said David Cohen, acting undersecretary for terrorism and financial intelligence, also will stress the need for tough implementation of sanctions against Iran to prevent it from setting up financial networks that could be used to further its nuclear ambitions.Cohen will meet in Ankara and Istanbul between Sunday and Thursday with private-sector representatives to make them aware that foreign banks doing business with countries like Iran risk losing access to the U.S. financial system, Treasury said.Rebels in Libya, with NATO help, are trying to oust long-time leader Muammar Gaddafi.